JP3060806B2 - Liquid crystal display device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG.
This will be described below using (a) to (d).

In a first step, an SiO2 film 2 is formed as an undercoat film on a glass substrate 1 as an insulating transparent substrate.
Is formed over the entire surface. Next, in a second step, an Al film or an Al alloy film, for example, is pattern-formed on the substrate as a first metal film to be the gate electrode 3. At this time, the gate-side TAB mounting electrode 3a serving as a signal input lead electrode is led out to the extended end of the gate wiring and is arranged with the same gate material (see FIG. 6A).

Next, in a third step, a gate insulating film 4, a silicon semiconductor layer 5, and a channel protective film 6 are formed.
In the fourth step, the channel protective film 6 on the gate electrode 3 is patterned. Next, in a fifth step, an n +: silicon film (not shown) is formed, and the n +: silicon film and the silicon semiconductor layer 5 are patterned so as to form a TFT in the future (see FIG. 6B).

In a sixth step, a transparent conductive film ITO is formed as a pixel electrode 7 to form a pattern (see FIG. 6C).

In a seventh step, a pattern of, for example, Ti / Al is formed as a second metal film to be the source / drain electrodes 8. At this time, the TAB mounting electrode on the source side as a signal input extraction electrode is extended to the extended end of the source wiring and is arranged with the same source material.

In an eighth step, an SiNx film serving as an insulating protection film 9 is formed, so that an interlayer insulating film 4 and a SiNx film serving as an insulating protection film 9 are mounted on the TAB mounting electrode 3a on the gate side. The SiNx film as the insulating protection film 9 is mounted on the TAB mounting electrode on the source side.

Finally, as a ninth step, the insulating protective film 9 is formed.
Is patterned. At this time, the SiNx film serving as the interlayer insulating film 4 and the insulating protective film 9 is etched and removed by, for example, dry etching with SF ₆ gas to expose individual electrode materials, thereby completing the TFT array substrate 10 ( FIG. 6D).

Then, TAB mounting is performed on the mounting electrode portions of the gate and the source, and a signal input electrode is drawn out.

FIGS. 7A and 7B show a TAB mounting structure.
(B). TAB is a TAB electrode 12 printed on an organic film 11 and the mounting electrode 3 on the TFT array substrate side.
a are electrically connected through conductive particles 14 contained in the adhesive anisotropic film 13. After that, for protection, for example, a silicone resin 15 is applied around the TAB mounting and cured to complete.

[0011]

An undercoat film of a liquid crystal display device is located between a glass substrate and a transistor layer formed in a subsequent process, and is generally used as a film for preventing contamination from a glass substrate to a transistor. I have. Also, when the gate and source extraction electrodes of the liquid crystal display device are directly extracted with Al or an Al alloy film,
There was a problem that Al was easily corroded in a wet environment test.

[0012]

In order to solve the above-mentioned problems, a liquid crystal display device according to the present invention, in which a gate electrode and a source electrode are directly drawn to the outside, comprises a metal film serving as a gate electrode and a source / drain electrode. Metal film is Ti and Al
And a laminated film of

[0013]

According to the structure of the present invention, the gate electrode is made of Ti.
By using / Al, the adhesion between Al and glass is improved by the first layer of Ti. The gate electrode Ti
/ Al is processed by dry etching, and the resist can be used as a buffer layer that avoids etching of the glass at the time of processing the gate electrode and prevents contamination of the transistor portion from the glass substrate by using a dedicated release agent. Gate and source
The lead electrode material for TAB mounting of the drain electrode is Ti / Al
Alternatively, it is possible to form TAB by forming a laminated film of Ti / Al alloy film.
It has an effect such that the potential difference from the side electrode material can be secured to control Al corrosion.

Further, by directly drawing out the gate electrode and the source electrode to the outside without conversion through another metal film, the contact window forming step becomes unnecessary and the number of steps can be reduced. Also, TAB
The mounting electrode material is Ti and the source and drain electrodes are Ti
By using a laminated film of / Al or Ti / Al alloy film, it is possible to reduce the size of the TAB mounting electrode pattern and the mounting resistance.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention is shown in FIGS.
This will be described below using (d).

First, as a first step, a Ti / Al or Ti / Al alloy film or a T / Al alloy film as a first metal film to be a gate electrode 3 is formed on, for example, a glass substrate 1 as an insulating transparent substrate.
A laminated film of i / Al / Ti or Ti / Al alloy film / Ti is formed. At this time, Al or Al / Ti is formed as a gate electrode using a glass substrate on which Ti is already formed on an insulating transparent substrate (not shown).

Next, a resist pattern is formed, and in the case of a two-layer film, pattern processing is performed by dry etching using a gas such as Cl ₂ or BCl _3, and in the case of a three-layer film, SF ₆ and Cl ₂ or Pattern processing is performed by dry etching using a gas of BCl ₃ or CHCl ₃ . After that, the resist is removed with a resist-specific release agent. At this time, the gate-side TAB mounting electrode 3a is led out to the extended end of the gate wiring and is arranged with the same gate material (see FIG. 1A).

Next, as a second step, a gate insulating film 4, a silicon semiconductor layer 5, and a channel protective film 6 are formed as in the conventional example. As a third step, the channel protective film 6 on the gate electrode 3 is patterned. Next, as a fourth step, an n +: silicon film 6 is formed, and the n +: silicon film 6 and the silicon semiconductor layer 5 are patterned so as to form a TFT in the future (see FIG. 1B).

As a fifth step, a transparent conductive film ITO is formed as a pixel electrode 7 to form a pattern (see FIG. 1C).

As a sixth step, source / drain electrodes 8
Ti / Al or Ti / Al alloy film or Ti / Al / Ti or Ti / Al alloy film / Ti
Is formed. Next, a resist pattern is formed,
As described above, a gas such as Cl ₂ or BCl ₃ is used for a two-layer film, and SF ₆ and Cl ₂ or BCl ₃ , C
Pattern processing is performed by dry etching using HCl ₃ gas. At this time, the TAB mounting electrode 8a on the source side is used.
Is drawn out to the extended end of the source wiring and is arranged with the same source material.

Then, as an eighth step, a SiNx film is formed as the insulating protection film 9 to thereby form the TAB on the gate side.
The SiNx film as the interlayer insulating film 4 and the insulating protection film 9 is mounted on the mounting electrode, and the SiNx film as the insulating protection film 9 is mounted on the TAB mounting electrode on the source side.

Finally, as a ninth step, the insulating protective film 9 is patterned. At this time, the SiNx film as the interlayer insulating film 4 and the insulating protective film 9 is etched and removed by, for example, dry etching with SF ₆ gas to expose individual electrode materials, and the thin film transistor array substrate 1
0 is completed (see FIG. 1D).

The correlation between the TAB side metal and the array electrode metal in such a TAB mounting of the TFT array was evaluated by an electrochemical method. First, FIG. 2 shows an evaluation system using a potentiogalvanostat. Ag / AgCl as reference electrode, Pt as counter electrode, KCl aqueous solution or Na ₂ S as electrolyte
A voltage was applied to various metal films using an O ₄ aqueous solution, and the electrode potential was measured. Au, S which is the plating material of the TAB electrode
n, Al and Ti / Al, which are array electrode materials, and polarization curves of these metals are shown in FIGS. As a result, when Au and Sn are cathode-polarized at 50 mv / sec, a reduction current starts flowing when Au is applied with a lower voltage than Sn. On the other hand, the equilibrium potential of Al is about -0.62 V with respect to Ag. 50mv
When anodic polarization is performed at / sec, an oxidation current flows with the elution of Al. On the other hand, in any case of Ti＼Al, an oxidation current starts to flow further on the anode side than Al in any electrolytic solution. And it proved that the potential difference was kept large in correlation with the TAB plating material, the oxidation current value was small, and it was difficult to dissolve.

FIG. 5A shows a second embodiment of the present invention.
This will be described below with reference to FIG.

In the first embodiment, a gate / source / drain electrode material has a two-layer structure of Ti / Al.
In this embodiment, the upper layer Ti layer is dry-etched by, for example, SF ₆ gas together with the SiNx film as the interlayer insulating film 6 and the insulating protection film 9 in the final step of forming the insulating protection film pattern in the three-layer structure of Ti / Al / Ti. Remove by etching. As a result, the Al material is exposed on the individual electrode surfaces, and the thin film transistor array substrate 10 is completed.
(D)).

The upper layer Ti of the three-layer structure is used as an Al hillock control film by a thermal process in the case of a gate electrode, and is developed by a photo process in a post-transparent electrode structure, ie, an ITO / source / drain structure in the case of source and drain electrodes. It is effective as an electrolytic corrosion prevention film by liquid. In addition,
The electrode structure composed of the laminated film of Ti and Al is not limited to the continuous film formation.

Further, in the first and second embodiments, the electrode structure is divided into a two-layer structure and a three-layer structure. However, the structure of the gate electrode, the source and the drain electrode may be selected as required. .

Although the undercoat film forming step is omitted in this embodiment, it goes without saying that there is no problem even if a glass substrate in which an SiO2 film is formed in advance on an insulating transparent substrate is used.

[0029]

According to the constitution of the present invention, the adhesion between Ti, Al and glass can be improved by forming the first layer of the gate electrode with Ti. In addition, the laminated film of Ti / Al of the gate electrode is processed by dry etching, and the resist uses a special release agent to avoid etching of the glass at the time of processing the gate electrode. Can be a buffer layer for preventing Therefore,
The undercoat film, which is conventionally required, is not required, and the number of steps can be reduced. Also, the lead electrode material for TAB mounting of the gate and source / drain electrodes is made of Ti / Al or Ti.
/ Al alloy film or a laminated film of Ti / Al / Ti to secure the potential difference from the TAB side electrode material
Corrosion can be suppressed. Al corrosion is particularly effective in correlation with an Au-plated TAB electrode, and a highly reliable liquid crystal display device can be obtained.

Furthermore, the external extraction of the gate electrode and the source electrode is directly extracted to the outside without conversion through another metal film, so that the step of forming a contact window becomes unnecessary, and the number of steps can be further reduced. . Also, by forming the TAB mounting electrode material with the same metal film as the gate and source / drain electrodes, a Ti / Al or Ti / Al alloy film or a laminated film of Ti / Al / Ti, the mounting resistance is reduced, and the TAB is reduced. The mounting electrode pattern can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first array process according to an embodiment of the present invention.

FIG. 2 Electrochemical evaluation system

Fig. 3 Polarization curve results

FIG. 4 Polarization curve results

FIG. 5 is a sectional view of a second array process according to the embodiment of the present invention.

FIG. 6 is a sectional view of a conventional array process.

FIG. 7 is a cross-sectional view of a conventional array in a TAB mounting configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Undercoat film 3 Gate electrode 4 Gate insulating film 7 Pixel electrode 8 Source / drain electrode 9 Insulation protective film

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 29/786 G02F 1/1365

Claims (5)

(57) [Claims] In a liquid crystal display device forming a thin film transistor array, a signal of a gate electrode of the thin film transistor is provided.
The external extraction electrode for signal input is directly
And electrically connected to the mounting electrodes without intervening other metal films
The electrode configuration of the gate electrode is a lower layer Ti and an upper layer Al
Laminated film or laminated film of lower Ti and upper Al alloy
A liquid crystal display device comprising a laminated film . 2. A liquid crystal forming a thin film transistor array.
In a display device, a signal of a gate electrode of a thin film transistor is used.
The external extraction electrode for signal input is directly
And electrically connected to the mounting electrodes without intervening other metal films
The electrode configuration of the gate electrode is a lower layer Ti and a middle layer Al
And upper layer Ti or laminated layer of lower layer Ti and middle layer Al alloy and upper layer
That any one of the stacked films of the layer Ti
Characteristic liquid crystal display device . 3. A liquid crystal forming a thin film transistor array.
In the display device, the signal of the source electrode of the thin film transistor is used.
The external extraction electrode for signal input is directly
Is electrically connected to the mounting electrode, and is electrically connected to the source electrode.
The electrode configuration is a laminated film of lower Ti, middle Al and upper Ti
Is any of the stacked films of lower Ti, middle Al alloy and upper Ti
Liquid crystal display device characterized by comprising a multilayer film
Place . 4. A liquid crystal forming a thin film transistor array.
In a display device, a signal of a gate electrode of a thin film transistor is used.
The external extraction electrode for signal input is directly
In this case, the external lead-out electrode does not pass through another metal film,
The electrode is electrically connected to the AB electrode by conductive particles.
The electrode configuration of the gate electrode is a laminated film of lower Ti and upper Al or
Is a laminated film of the lower Ti and the upper Al alloy
A liquid crystal display device comprising: 5. A liquid crystal forming a thin film transistor array.
In a display device, a signal of a gate electrode of a thin film transistor is used.
The external extraction electrode for signal input is directly
In this case, the external lead-out electrode does not pass through another metal film,
The electrode is electrically connected to the AB electrode by conductive particles.
The electrode configuration of the lower electrode is the lower layer Ti, the middle layer Al, and the upper layer Ti.
Laminated film or lamination of lower layer Ti, middle layer Al alloy and upper layer Ti
Liquid characterized by being composed of any one of laminated films of a film
Crystal display device.