JPH06110085A - Active matrix panel and its manufacture - Google Patents

Abstract

PURPOSE:To provide the active matrix panel which has a small defect in aluminum wiring in a manufacture process and its manufacture. CONSTITUTION:A wiring electrode 10 is made of aluminum and provided from the ohmic contact layer 9 of a TFT 3 to the pixel electrode 14 of a pixel part 2, and the TFT 3 and pixel electrode 14 are mutually connected. Then an oxide film 11 which is provided on the top surface of the wiring electrode 10, is formed by producing ozone while the wiring electrode 10 is irradiated with ultraviolet rays and then exposing the electrode to the atmosphere, and minuter than a natural oxide film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix panel and a method for manufacturing the same, and more particularly to an active matrix panel and a method for manufacturing the same, in which reliability of wiring between a thin film transistor as a switching element and a pixel electrode is improved.

[0002]

2. Description of the Related Art Conventionally, as one of typical image display devices called an active matrix panel, there is one using a liquid crystal element. That is, such an active matrix panel has a switching element for controlling the driving of the liquid crystal element, a liquid crystal element, and wiring between the switching element and the liquid crystal element and the like as main constituent elements (for example, "SID"). 91 Digest pp21
5 ~ 218 ", etc.). In such an active matrix, a pixel electrode forming a liquid crystal element and a thin film transistor are connected by an aluminum (Al) wiring, and this aluminum wiring does not have an interlayer insulating film, and a part of its surface serves as a pixel electrode. It comes in direct contact. Conventionally, as a manufacturing process of such a structure, indium tin oxide (ITO) is used as a pixel electrode.
Was deposited and patterned, and then a laminated film of Al or a diffusion barrier metal of Al and Si was deposited and patterned.

By the way, the above manufacturing process has the following problems. That is, after the Al film is formed, an etching process using an aqueous solution for patterning, that is, a so-called wet process is performed. In this case, as shown in FIG. In some cases, a phenomenon may occur in which the ITO electrode 21 is eroded due to the progress of etching from the boundary surface part. This is because the above phenomenon does not usually occur when the same wet etching process is performed on only Al, but there is a portion where the Al electrode 22 and the ITO electrode 21 are in contact with each other as shown in FIG. This Al electrode 22
And locally battery between the ITO electrodes 21 are formed, a type of electrochemical reaction occurs between the aqueous solution for wet treatment, Al is a Mizuyo of H ₂ AlO ₃ ^- to change And then dissolves in the aqueous solution, as shown in FIG.
It is considered that the film is formed and finally the ITO electrode 21 is etched. In particular, with respect to Al, the above-described abnormal etching may occur even when Cl gas used for etching remains. The abnormal etching portion generated in this manner easily causes disconnection of the aluminum wiring portion, and there is a problem that the product yield is reduced. The occurrence of abnormal etching due to the relationship between the solution used for this wet treatment and the wiring material or pixel electrode material is theoretically
This can be avoided by changing the wiring material and the pixel electrode material.

[0004]

However, the wiring material Al is an indispensable material for wire bonding, and ITO is currently the lowest resistance and most stable transparent member. There is currently no suitable alternative material. Therefore, it is possible to avoid the above-described abnormal etching by providing an interlayer insulating film between Al and ITO so as to prevent the ITO from being exposed. However, it is possible to use ITO as a hydrofluoric acid-based etchant for the interlayer insulating film. However, there is a problem that the contact resistance is increased for a long time, resulting in an increase in contact resistance.

As a means for solving such inconvenience, for example, in Japanese Patent Laid-Open No. 58-178562, ITO is formed after Al is provided to avoid damage in Al which occurs when etching ITO. For A
Although a technique for anodizing the surface of the l-wiring is disclosed, this method tends to increase the thickness of the oxide film, which increases the contact resistance between ITO and Al, thereby writing charges to the liquid crystal element. There was a problem that it would be difficult.

The present invention has been made in view of the above circumstances, and provides a highly reliable active matrix panel in which defects of aluminum wiring are less likely to occur in the manufacturing process and a manufacturing method thereof.

[0007]

In order to solve the above problems, an active matrix panel according to a first aspect of the present invention has a plurality of liquid crystal elements and switching elements connected to the liquid crystal elements, and the switching is performed. In the active matrix panel in which the element and the transparent electrode made of indium tin oxide forming the liquid crystal element are connected by a wiring electrode made of aluminum and partly laminated on the transparent electrode, the wiring electrode is A protective layer made of an etching resistant member is provided on the surface opposite to the contact surface with the transparent electrode. In particular, the protective layer made of the etching resistant member is preferably an oxide film formed in the gas phase. Further, the method of manufacturing an active matrix panel according to the invention of claim 3 has a plurality of liquid crystal elements and switching elements connected to the liquid crystal elements, and the indium oxide forming the switching elements and the liquid crystal element. In the method for manufacturing an active matrix panel in which a transparent electrode made of tin is connected by a wiring electrode made of aluminum and partly laminated on the transparent electrode, aluminum and an etching resistant member are formed after the transparent electrode is formed. After depositing in order,
The aluminum is formed into a desired shape by wet etching, and then the etching resistant member formed on the aluminum is removed in a desired range. The method for manufacturing an active matrix panel according to a fourth aspect of the present invention has a plurality of liquid crystal elements and a plurality of switching elements connected to the liquid crystal elements, the indium oxide forming the switching elements and the liquid crystal element.
A transparent electrode made of tin, a method of manufacturing an active matrix panel, which is made of aluminum and is partially connected to the transparent electrode by a wiring electrode, in which aluminum is deposited after the transparent electrode is formed,
While irradiating the deposited aluminum surface with ultraviolet rays, the aluminum is exposed to an atmosphere of ozone generated by this irradiation to form an oxide film on the aluminum surface,
The aluminum layer is formed into a desired shape by wet etching.

[0008]

In the active matrix panel according to the first aspect of the present invention, the etching progresses due to the electrochemical reaction formed on the aluminum, that is, between the aluminum and the transparent electrode. The layer of the member that does not perform a role of a protective layer for preventing the progress of etching from the surface of the aluminum to the indium tin oxide on the lower surface of the aluminum when the aluminum is wet-etched. In the active matrix panel according to the second aspect of the present invention, the oxide film formed on the aluminum is such that, when the aluminum is wet-etched, the indium tin oxide from the surface of the aluminum to the lower surface of the aluminum. It plays a role of a protective layer for preventing the progress of etching. In the method of manufacturing an active matrix panel according to the third aspect of the present invention, an etching resistant member is deposited on the aluminum layer to protect the aluminum surface and then the aluminum is patterned by wet etching. Therefore, it is possible to prevent unnecessary corrosion of the aluminum surface during wet etching. In the method for manufacturing an active matrix panel according to the fourth aspect of the present invention, the aluminum is patterned by wet etching after forming an oxide film by ultraviolet irradiation on the aluminum. This will prevent unwanted erosion from the aluminum surface.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An active matrix panel according to the present invention and a method for manufacturing the same will be described below with reference to FIGS. Here, FIG. 1 is a vertical sectional view showing an embodiment of the active matrix panel according to the present invention, and FIG. 2 is a partially enlarged vertical sectional view of a wiring electrode and an oxide film in the embodiment shown in FIG. . The basic structure of this active matrix panel is the same as that of a conventional active matrix panel, except for an oxide film formed on the surface of a wiring electrode described later. That is, the active matrix panel has a pixel portion 2 formed of a liquid crystal element on an insulating substrate 1.
And a thin film transistor (hereinafter referred to as “TFT”) 3 connected to the liquid crystal element of the pixel unit 2 as a basic unit, and a plurality of these are arranged in a matrix form. A vertical cross-section of is shown. In the embodiment shown in FIG. 1, the connection pad 12 is provided on the left side of the TFT 3, and the connection pad 12 is connected to the wiring electrode 10 at a portion (not shown). By connecting the wiring from the circuit (not shown), the active matrix panel and the external circuit are connected. Although the oxide film 11 is formed on the upper surface of the connection pad 12 like the wiring electrode 10, the oxide film 11 is formed.
Is necessarily removed when wiring from an external circuit or the like is connected to the connection pad 12 by, for example, an ultrasonic welding method, so that no special removal treatment is required. Is.

In this embodiment, the gate electrode 4 is provided on the insulating substrate 1, and the anodic oxide film 5 is formed on the upper surface of the gate electrode 4. Then, while covering the gate electrode 4 and the anodic oxide film 5, the insulating substrate 1
A gate insulating film 6 is laminated so as to cover a part of the gate insulating film 6.
Further, a part of the gate insulating film 6, that is, the TFT
The active layer 7 and the channel protective layer 8 are provided in the part constituting
Are sequentially laminated, and the ohmic contact layer 9 is laminated so as to cover the side edges of the active layer 7 and the channel protective layer 8. Further, on the active layer 7, a wiring electrode 10 and an oxide film 11 as a layer composed of an etching resistant member are sequentially laminated, and a protective film 13 is further provided so as to cover the whole. On the other hand, in the pixel portion 2, the pixel electrode 14 is laminated on the gate insulating film 6 described above. A part of the pixel electrode 14 is the wiring electrode 1 described above.
This wiring electrode 10 is covered by
Serves as a wiring electrode between the TFT 3 and the pixel electrode 14. An oxide film 11 is also formed on the upper surface of the connection pad 12, but since the oxide film 11 is extremely thin, it does not affect the contact resistance. The oxide film 11
Is the wiring electrode 10 made of aluminum as described later.
The layer serves as a layer made of an etching resistant member that does not cause etching to proceed with an electrochemical reaction that occurs between the ITO and the pixel electrode 14 made of ITO.

Next, a manufacturing process of the active matrix panel having the above-mentioned structure will be described. First, a metal member (for example, aluminum) forming the gate electrode 4 is deposited and patterned on the insulating substrate 1 by a vapor deposition method or the like to form the gate electrode 4, and then the gate electrode 4 is formed. The anodic oxide film 5 is formed on the upper surface of the cathode electrode 4 by anodic oxidation. Next, for example, SiNx forming the gate insulating film 6, a-Si: H forming the active layer 7, and SiNx forming the channel protective layer 8 are successively deposited by plasma CVD, and the back surface of the insulating substrate 1 ( Back surface exposure is performed from the lower side of the paper in FIG. 1 to pattern the SiNx forming the channel protective layer 8 to form the channel protective layer 8 and the a-Si: H forming the active layer 7 in a self-aligned manner. The active layer 7 is obtained by forming.

Then, n + a-Si forming the ohmic contact layer 9 is deposited and patterned to form source / drain regions 7a and 7b. Further, subsequently, ITO forming the pixel electrode 14 is deposited and patterned to form the pixel electrode 14. Next, Al (aluminum) is deposited to a thickness of about 1 μm by sputtering. Then, after depositing the Al film, UV light (ultraviolet light) is irradiated to emit O3.
The surface of Al is oxidized by exposing it to an atmosphere in which (ozone) is generated for about 10 minutes to obtain an oxide film 11. The oxide film 11 obtained by this oxidation treatment is denser than the natural oxide film, and the surfaces of the joints of the aluminum grains 20 forming the wiring electrodes 10 are surely covered (see FIG. 2). It prevents the Al surface from acting as an electrode in the wet treatment of
It acts as a barrier to the abnormal etching caused by the battery formed between and.

After that, Al is patterned by wet etching to form the wiring electrode 10, and then SiNx to be the protective film 13 is deposited by the plasma CVD method, and the connection pad 12 is patterned. Thus, the protective layer 13 is formed to complete the active matrix panel. In this embodiment, the surface of Al is irradiated with UV light, and the oxide film 11 is formed on the Al surface by exposing Al to the resulting O3. However, the present invention is not limited to this method, and oxygen plasma may be used. 2 in an atmosphere containing treatments and oxygen
A method of heat treatment at about 00 degrees may be used. Also,
The member forming the wiring electrode 10 is S instead of aluminum.
It may be an aluminum alloy containing i, Ti, Cu and the like. Although the wiring electrode 10 and the pixel electrode 14 are directly joined to each other, the wiring electrode 10 made of aluminum is used.
The contact resistance between the wiring electrode 10 and the pixel electrode 14 may be further reduced by providing a layer made of Mo (molybdenum) between the pixel electrode 14 and the pixel electrode 14 made of ITO.

Next, a second embodiment will be described with reference to FIG. The same components as those of the first embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. Hereinafter, different points will be mainly described. In the second embodiment, the oxide film is formed on the surface of the wiring electrode made of Al in the first embodiment, whereas the etching protection film 15 made of Mo is provided on the surface of the wiring electrode made of Al. The difference is that it is different from the first embodiment. Where A
Mo laminated on the layer 1 serves as a barrier against abnormal etching caused by the formation of a cell locally between Al and ITO.

Next, the manufacturing process of the active matrix panel having the above-mentioned structure will be described focusing on the points different from the first embodiment. That is, also in the second embodiment, the manufacturing process until the pixel electrode 14 is formed is
It is the same as in the first embodiment shown in FIG. After the pixel electrode 14 is formed, A is formed by sputtering.
In the order of 1 and Mo, Al is about 1 μm and Mo is about 500.
About angstrom is applied to each film. Where M
For the deposition film of o, the same etchant as that used for the Al deposition film is used as it is, and is continuously etched to perform patterning to form the wiring electrode 10 and the etching protection film 15. After that, SiNx forming the protective film 13 is deposited by the plasma CVD method to form the connection pad 1
The portion 2 is patterned to form the protective film 13. Finally, Mo exposed on the upper surface of the connection pad 12 is removed to complete the active matrix panel.

In this embodiment, M is formed on the upper surface of Al.
Although the etching protection layer 15 made of o is provided, the member forming the etching protection film 15 is not limited to Mo, and aluminum of the wiring electrode 10 and I of the pixel electrode 14 are not necessary.
As a matter of course, another member may be used as long as it can reduce the contact potential difference generated with the TO or suppress the reaction. Specifically, for example, Ta, W, etc. are suitable as a substitute for Mo.

Further, in the above two embodiments,
The active matrix panel having TFTs made of a-Si has been described as an example, but the present invention is not limited to the active matrix panel having the structure of the above-described embodiment, and a structure in which Al and ITO are in direct contact with each other. It is applicable as long as it is an active matrix panel having.

According to the present invention, ozone is generated by irradiating the surface of aluminum, which is a wiring electrode that comes into contact with ITO, with ultraviolet rays, and aluminum is exposed to the atmosphere to form a dense oxide film on the surface of aluminum. In this way, since the surface of the aluminum is protected, in the wet treatment at the time of patterning the aluminum, the pinhole of aluminum, which has been conventionally generated, and the corrosion of ITO are eliminated. Therefore, the yield of the product is improved and the reliability is improved.

[0019]

As described above, according to the first and third aspects of the present invention, by forming the layer made of the etching resistant member on the wiring electrode made of aluminum, the aluminum is formed. Since the layer of the etching resistant member prevents the progress of the etching from the surface of the indium tin oxide to the surface of the indium tin oxide, the occurrence of the disconnection of the wiring electrode made of aluminum can be prevented, and the yield at the manufacturing stage can be improved. It is possible to provide an active matrix panel that is improved and highly reliable. According to the inventions of claims 2 and 4, by forming an oxide film having an extremely thin film thickness on the wiring electrode made of aluminum, etching from the surface of the aluminum toward the indium tin oxide is performed. Since the oxide film prevents the progress, it is possible to prevent the occurrence of the cause of the disconnection of the wiring electrode made of aluminum,
It is possible to improve the yield in the manufacturing stage and to provide an active matrix panel with high reliability.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a main part of an active matrix panel according to the present invention.

FIG. 2 is a partial vertical cross-sectional view showing the vicinity of an oxide film in the active matrix panel shown in FIG.

FIG. 3 is a vertical cross-sectional view showing another embodiment of the active matrix panel according to the present invention.

FIG. 4 is a vertical cross-sectional view illustrating an abnormal etching phenomenon in a conventional active matrix panel.

[Explanation of symbols]

10 ... Wiring electrode, 11 ... Oxide film, 14 ... Pixel electrode,
15 ... Etching protective film

Claims (4)

[Claims] 1. A liquid crystal element and a plurality of switching elements connected to the liquid crystal element, wherein the switching element and the transparent electrode made of indium tin oxide forming the liquid crystal element are made of aluminum and In an active matrix panel in which parts are connected by wiring electrodes laminated on the transparent electrodes, the wiring electrodes are provided with a layer made of an etching resistant member on a surface opposite to a contact surface with the transparent electrodes. An active matrix panel characterized by the above. 2. A liquid crystal element and a plurality of switching elements connected to the liquid crystal element, wherein the switching element and the transparent electrode made of indium tin oxide forming the liquid crystal element are made of aluminum and In an active matrix panel in which parts are connected by wiring electrodes laminated on the transparent electrode, the wiring electrode is provided with an oxide film formed in a vapor phase on a surface opposite to a contact surface with the transparent electrode. An active matrix panel characterized by being formed. 3. A liquid crystal element and a plurality of switching elements connected to the liquid crystal element, wherein the switching element and the transparent electrode made of indium tin oxide forming the liquid crystal element are made of aluminum and In a method for manufacturing an active matrix panel in which a portion is connected by a wiring electrode laminated on the transparent electrode, aluminum and an etching resistant member are sequentially deposited after the formation of the transparent electrode, and then the aluminum is wet-etched to a desired thickness. A method for manufacturing an active matrix panel, which comprises forming into a shape, and then removing the etching resistant member formed on the aluminum in a desired range. 4. A liquid crystal element and a plurality of switching elements connected to the liquid crystal element, wherein the switching element and the transparent electrode made of indium tin oxide forming the liquid crystal element are made of aluminum and In a method for manufacturing an active matrix panel, in which parts are connected by wiring electrodes laminated on the transparent electrode, aluminum is deposited after formation of the transparent electrode, and the deposited aluminum surface is irradiated with ultraviolet rays, A method for manufacturing an active matrix panel, which comprises exposing the aluminum to an atmosphere of generated ozone to form an oxide film on the aluminum surface, and then forming the aluminum layer into a desired shape by wet etching.