JPH07120789A - Liquid crystal display device and its production - Google Patents

Abstract

PURPOSE:To prevent corrosion of terminals and to obtain an active matrix substrate having terminals of high reliability by laminating a conductive oxide film or conductive nitride film on a conductive oxide film, conductive nitride film or at least one layer of metal film and forming terminals for wiring with using the same mask. CONSTITUTION:An Al film is deposited on a glass substrate 1 and a resist mask is formed to etch the film and then removed to obtain a scanning electrode wiring 2. Then a silicon nitride film, an amorphous silicon (a-Si) film, and an a-Si containing P (n+a-Si) film are deposited on the substrate. A resist mask is formed to etch the a-Si film and the semiconductor film containing impurities into an inland shape to obtain a-Si layer 4 and a n+a-Si layer 5. Then the silicon nitride film is etched to obtain the pattern of a gate insulating film 3. Further, laminated films of ITO and Cr are etched in a wet state to form a source electrode 7, electrode wiring 6 for picture signals, and counter electrode wiring 8.

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 device, and more particularly to an active matrix substrate using a non-linear element, a method of manufacturing the same, and a liquid crystal display device driven using the active matrix substrate.

[0002]

2. Description of the Related Art JP-B-63-21907 discloses that a transparent conductive film such as ITO is always used as an electrode in a pixel by applying an electric field in a direction parallel to a thin film transistor substrate when driving liquid crystal molecules. A liquid crystal display device is shown that does not require it.

In the liquid crystal display device of the type disclosed in Japanese Patent Application Laid-Open No. 3-58019 in which a driving electric field is applied vertically to a substrate, the pixel electrode is formed of a transparent conductive film in order to see the light transmitted through the pixel electrode. There is a need to. However, Japanese Examiner's Sho 63-21
In the liquid crystal display device of the method of the 907 publication, since the light passing through the gap between the pair of electrodes applying the driving electric field is seen,
The electrodes need not be translucent.

[0004]

In the liquid crystal display device having the structure of JP-B-63-21907, the structure of the terminals of the electrodes arranged in a matrix has not been clarified. With this structure, there is no need to use a transparent conductive oxide film such as ITO, so if the connection terminal with the external drive circuit is made of the same metal as the wiring, it will be corroded by the chemical solution during the process and the metal of the terminal will corrode and reduce reliability. Is concerned. Although the terminal can be formed in a separate step by using a metal resistant to corrosion, there is a problem that the metal resistant to corrosion is difficult to process and expensive.

Japanese Unexamined Patent Publication (Kokai) No. 3-58019 discloses a terminal which has Al in a wiring portion in a protective film and has a laminated structure of any one of Ta, Cr and Ti and ITO, or an ITO single layer structure. It is disclosed. However, the metal single layer has a problem that corrosion occurs due to a chemical solution during the process, or a connection resistance with an external peripheral circuit increases due to a high resistance surface oxide film generated during heat treatment during the process. When the laminated structure is used, the conductive oxide covering the terminal metal is also used for forming the pixel electrode, and therefore Ta and C are used for forming the wiring and the terminal portion.
There is a problem that one of r and Ti, Al, and ITO must be processed a total of three times, which makes the process long and complicated.

When the terminals are formed of a single layer of ITO,
Since ITO is also used for forming a pixel electrode, it must be transparent. Visible light is attenuated to a brightness of 50% or less when transmitted through a color filter or the like provided in the liquid crystal display device, and thus the visible light transmittance of the pixel electrode is preferably as high as possible, and more preferably 85% or more. However, in order to increase the transmittance, it is necessary to strictly control the film forming conditions and make the film thickness thin. In the generally widely used ITO, as shown in FIG. 2, the sheet resistance rapidly increases in the region where the transmittance is 85% or more. Therefore, when a terminal is formed using a transparent conductive film such as ITO used for the pixel electrode, there is a problem that the terminal resistance increases and the image quality deteriorates.

An object of the present invention is to provide a structure of a liquid crystal display device provided with an active matrix substrate having highly reliable terminals and a manufacturing method thereof.

[0008]

In the conventional liquid crystal display device for driving a liquid crystal by applying an electric field having a component parallel to the active matrix substrate, the object of the above paragraph is to provide a conductive oxide film or a conductive oxide film as shown in FIG. By forming a conductive nitride film or by laminating a conductive oxide film or a conductive nitride film on at least one or more metal films and processing them with the same mask to form electrodes and wirings and terminals or only terminals. To be achieved.

[0009]

By forming the uppermost layer of the terminal by using a conductive oxide or conductive nitride that is resistant to corrosion, corrosion due to the chemical solution during the process is prevented and the reliability of the terminal is improved.

Although the transmittance of the conductive oxide is less than 85%, the wiring resistance or the terminal resistance can be reduced by using a film having a low resistance. Alternatively, the wiring resistance or the terminal resistance can be similarly reduced by using a conductive oxide film or a conductive nitride film having a different composition such as molybdenum oxide or titanium nitride which is opaque but has low resistance.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing process of an active matrix substrate to which the present invention is applied will be described below with reference to the drawings.

(Embodiment 1) FIG. 3 is a plan view showing an active matrix substrate. 4 to 7 are views showing the manufacturing process of the thin film transistor provided on the active matrix substrate, using the cross section taken along the line AA 'in FIG. 8 to 11 are views showing a manufacturing process of terminals of scan electrode wirings (hereinafter referred to as gate electrode wirings) of the active matrix substrate by using the vertical section taken along line BB 'in FIG. FIG. 12 is a cross-sectional view showing the structure of the terminals of the image signal electrode wiring and the counter electrode wiring of the CC ′ active matrix substrate in FIG.

(1) (See FIG. 4) An Al film having a thickness of 300 nm is deposited on the glass substrate 1 by a sputtering method. A resist mask is formed by using a normal photolithography technique, etching is performed, and then the resist mask is removed.
The scan electrode wiring 2 made of a film is created.

(2) (See FIG. 5) A silicon nitride film having a thickness of 200 nm and amorphous silicon (hereinafter abbreviated as a-Si) is formed on a substrate.
A-Si containing 100 nm of film and 1% P (hereinafter n
A + a-Si film is deposited to a thickness of 50 nm by a chemical vapor deposition method (hereinafter abbreviated as a CVD method). Next, a resist mask is formed using the photolithography technique, and a-
The Si film and the impurity-containing semiconductor film are etched and processed into an island shape to obtain an a-Si layer 4 and an n + a-Si layer 5. After removing the resist, a resist mask is formed by the photolithography technique, the silicon nitride film is etched to remove the resist, and the pattern of the gate insulating film 3 is obtained.

(3) (See FIG. 6) Cr is deposited to a thickness of 50 nm on the substrate by sputtering, and then ITO is deposited to a thickness of 100 nm.
accumulate. A resist mask is formed by using the photolithography technique, the laminated film of ITO and Cr is wet-etched, and then the resist mask is removed to form the source electrode 7, the image signal electrode wiring 6, and the counter electrode wiring 8.

(4) (See FIG. 7) A silicon nitride film is deposited to a thickness of 500 nm on a substrate by a CVD method, a resist mask having a predetermined pattern is formed by using a photolithography technique, and etching is performed to remove the resist pattern. The pattern of the insulating protective film 9 is formed.

Manufacturing process of the scanning electrode wiring terminal portion (5) (see FIG. 8) When forming the scanning electrode wiring in the step (1),
The scanning electrode wiring 2 is formed so that at least a part of the terminal formation region overlaps.

(6) (See FIG. 9) When the gate insulating film 3 is formed in the step (2), the gate insulating film 3 is formed in a pattern in which a part of the end of the scanning electrode wiring is exposed.

(7) Cr and IT in step (3) (see FIG. 10)
When forming the source electrode 7, the image signal electrode wiring 6, and the counter electrode wiring 8 by the laminated film of O, the scanning electrode wiring terminal 10 is formed so as to at least partially overlap the scanning electrode wiring 2 formed in the step (5). Form.

(See FIG. 11) When the insulating protective film 9 is formed in the step (4), the insulating protective film 9 is formed so as to overlap at least the gate insulating film 3 and not cover all the terminals 10.

After that, an alignment film and the like are formed to complete the liquid crystal display device.

Since the image signal electrode wiring and the counter electrode wiring (see FIG. 12) are formed by using a laminated film of ITO and Cr, each wiring and terminal are formed in a continuous pattern in the same process.

In this embodiment, since the source electrode, the image signal electrode wiring and the counter electrode wiring are formed by using the ITO / Cr laminated film, it is not necessary to form the terminals of each wiring in a separate process. Further, at the same time, the terminals of the scanning electrode wiring can be formed. When the metal forming the scan electrode wiring is a metal such as Al that is easily oxidized, the barrier metal between the ITO and the wiring metal is processed by the same mask, so that the contact between the terminal and the wiring is increased without increasing the number of steps. The resistance can be reduced.

Since the present invention is applied to a liquid crystal display device in which an electric field having a component parallel to the active matrix substrate is applied to drive the liquid crystal, the electrodes to which the electric field is applied need not be translucent. Therefore, when the wiring is formed by the laminated film as shown in this embodiment, the number of steps is smaller than that in the case where the wiring is formed only by using the ITO film having a resistance 10 times or more higher than that of the metal such as Al or Cr. The wiring resistance can be reduced without increasing the resistance.

(Embodiment 2) FIG. 13 is a sectional view of a terminal of a scan electrode wiring of an active matrix substrate. 14
FIG. 4 is a cross-sectional view of terminals of image signal electrode wirings and counter electrode wirings of an active matrix substrate.

In this embodiment, unlike the first embodiment, the contact hole 12 is provided on the upper surface of the terminal. By covering the side surface of the terminal composed of the laminated film in which the ITO 13 is overlaid on the Cr 14 with the insulating protective film 9, it is possible to prevent the metal of the laminated film of the terminal portion from touching the chemical solution in the process, and the metal on the side surface of the wiring is prevented. It has the effect of preventing corrosion.

In the above two embodiments, the image signal electrode wiring and the counter electrode wiring are formed by the laminated film of the conductive oxide film and Cr, but the same effect can be obtained by forming the scanning electrode wiring by the laminated film. . Instead of ITO used in the examples, conductive oxides such as indium oxide, tin oxide, zinc oxide, titanium oxide and zirconium oxide, or Ta, Cr, M are used.
The same effect can be obtained by using a conductive nitride containing at least one of o, Nb, V, Hf, and Zr as a base material.
The same effect can be obtained by using a conductive oxide single layer film such as ITO instead of the conductive oxide film and the metal laminated film. A similar effect can be obtained by using a conductive nitride film single layer film instead of the conductive nitride film and the metal laminated film. The same effect can be obtained even if the constituent material of each wiring used in the embodiment is a metal other than that used in the embodiment.

Further, although the inverted stagger type thin film transistor is used as a switching element in the embodiment, the same effect can be obtained when a stagger type or coplanar type transistor or a non-linear element such as a diode is used as a switching element. .

[0029]

According to the present invention, in a liquid crystal display device in which an electric field for driving liquid crystal molecules is applied in a direction parallel to the surface of a glass substrate, the wiring terminals are made of a conductive oxide film or a conductive nitride film, or at least Corrosion of the terminals can be prevented by forming a conductive oxide film or a conductive nitride film on one layer of the metal film and forming the stacked film using the same mask.

Although the visible light transmittance is lower than that of the conventional one,
Since a conductive oxide film or nitride film having low resistance can be used, the terminal resistance can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a scanning electrode wiring terminal to which the present invention is applied.

FIG. 2 is an explanatory diagram showing the relationship between the film thickness of ITO and the transmittance of visible light or sheet resistance.

FIG. 3 is a plan view showing an active matrix substrate to which the present invention is applied.

FIG. 4 is a cross-sectional view showing the thin film transistor in the manufacturing process of the first embodiment of the present invention.

FIG. 5 is a cross-sectional view showing the thin film transistor in the manufacturing process of the first embodiment of the present invention.

FIG. 6 is a cross-sectional view showing the thin film transistor in the manufacturing process of the first embodiment of the present invention.

FIG. 7 is a cross-sectional view showing the thin film transistor in the manufacturing process of Embodiment 1 of the present invention.

FIG. 8 is a cross-sectional view showing scan electrode wiring terminals in the manufacturing process of the first embodiment of the present invention.

FIG. 9 is a cross-sectional view showing the scan electrode wiring terminal in the manufacturing process of the first embodiment of the present invention.

FIG. 10 is a sectional view showing scan electrode wiring terminals in the manufacturing process of the first embodiment of the present invention.

FIG. 11 is a cross-sectional view showing the scan electrode wiring terminal in the manufacturing process of the first embodiment of the present invention.

FIG. 12 is a sectional view showing the image signal electrode wiring terminal and the counter electrode wiring terminal in the manufacturing process of the first embodiment of the present invention.

FIG. 13 is a sectional view showing a scan electrode wiring terminal according to a second embodiment of the present invention.

FIG. 14 is a sectional view showing an image signal electrode wiring terminal and a counter electrode wiring terminal according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... Scan electrode wiring, 3 ... Gate insulating film, 4 ... a-Si layer, 5 ... n + a-Si layer, 6 ... Image signal electrode wiring, 7 ... Source electrode, 8 ... Counter electrode wiring, 9 …
Insulating protective film, 10 ... Scan electrode wiring terminal, 11 ... Image signal electrode wiring terminal, 12 ... Contact hole, 13 ... IT
O, 14 ... Cr.

Claims (11)

[Claims] 1. A driving voltage applied to liquid crystal molecules sandwiched between a pair of substrates has a component parallel to the substrates, and a plurality of image signal electrode wirings, non-linear elements and counter electrode wirings are provided on one substrate. A liquid crystal display device comprising: a liquid crystal display device, wherein each wiring terminal on the substrate is formed using a conductive oxide film. 2. A driving voltage applied to liquid crystal molecules sandwiched between a pair of substrates has a component parallel to the substrates, and a plurality of image signal electrode wirings, non-linear elements and counter electrode wirings are provided on one substrate. In the liquid crystal display device including the above, each wiring terminal on the substrate is formed from a laminated film obtained by laminating a conductive oxide film on at least one conductive film and processing the same using the same mask. Liquid crystal display device. 3. A driving voltage applied to liquid crystal molecules sandwiched between a pair of substrates has a component parallel to the substrates, and a plurality of image signal electrode wirings, non-linear elements and counter electrode wirings are provided on one substrate. A liquid crystal display device including: a liquid crystal display device, wherein each wiring terminal on the substrate is formed using a conductive nitride film. 4. A driving voltage applied to liquid crystal molecules sandwiched between a pair of substrates has a component parallel to the substrates, and a plurality of image signal electrode wirings, non-linear elements and counter electrode wirings are provided on one substrate. In the liquid crystal display device including the above, each wiring terminal on the substrate is formed from a laminated film obtained by laminating a conductive nitride film on at least one conductive film and processing the same using the same mask. Liquid crystal display device. 5. The liquid crystal display device according to claim 1, 2, 3 or 4, wherein the terminal portion of each wiring and the wiring portion are manufactured in different steps. 6. The method according to claim 1, 2, 3, 4 or 5.
A liquid crystal display device in which at least a side surface of each wiring terminal is covered with a film made of at least one of an insulator, an oxide, and a nitride. 7. The liquid crystal display device according to claim 6, wherein a contact hole for electrically connecting to a lower conductive film is provided on an upper surface of the insulating film covering the terminal. 8. A driving voltage applied to liquid crystal molecules sandwiched between a pair of substrates has a component parallel to the substrates, and a plurality of image signal electrode wirings, non-linear elements and counter electrode wirings are provided on one substrate. A method of manufacturing a liquid crystal display device, comprising the following steps. A step of depositing at least one of an insulating film, an oxide film, and a nitride film on the substrate on which the wiring terminals of the image signal electrode wiring and the counter electrode wiring are formed. The film covers at least the side surface of each of the terminals,
A step of forming a pattern in which a part of the upper surface is opened. 9. The transmittance for visible light of the conductive oxide film according to claim 1, 2, 5, 6, 7 or 8, is 85%.
Liquid crystal display device which is less than. 10. Claims 1, 2, 5, 6, 7, 8 or 9
3. The liquid crystal display device according to, wherein the conductive oxide film is at least one of indium oxide, tin oxide, zinc oxide, Indium-Tin-Oxide, titanium oxide, zirconium oxide, and molybdenum oxide. 11. The conductive nitride film according to claim 3, 4, 5, 6, 7 or 8, wherein Ta, Cr, Mo, Nb,
A liquid crystal display device comprising a nitride containing at least one of V, Hf, and Zr as a base material.