JP3221094B2 - Active matrix panel and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an active matrix panel.
In connection with the manufacturing method , in particular, the reliability of the wiring between the thin film transistor as a switching element and the pixel electrode was improved.
The present invention relates to a method for manufacturing an active matrix panel .

[0002]

2. Description of the Related Art Conventionally, as a typical image display device called an active matrix panel, there is an image display device using a liquid crystal element. That is, such an active matrix panel includes a switching element for controlling driving of a liquid crystal element, a liquid crystal element, and wiring between the switching element and the liquid crystal element as main components (for example, “SID”). 91 Digest pp21
5 to 218 "). In such an active matrix, the connection between the pixel electrode constituting the liquid crystal element and the thin film transistor is made by aluminum (Al) wiring, and this aluminum wiring is partially connected to the pixel electrode without an interlayer insulating film. It comes into 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.

[0003] In the above-described manufacturing process, there are the following problems. That is, after the Al deposition, 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 occurs in which etching progresses from the boundary surface portion and the ITO electrode 21 is eroded. This is because the above-mentioned phenomenon does not usually occur when the same wet etching is performed only on 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
A battery is locally formed between the electrode and the ITO electrode 21, and a kind of electrochemical reaction occurs between the electrode and the aqueous solution for wet treatment, and Al changes into water-soluble H ₂ AlO ₃ ^−. To dissolve in the aqueous solution, and as shown in FIG.
Is formed, and it is considered that up to the ITO electrode 21 is finally etched. In particular, regarding Al, the above-described abnormal etching may occur even when Cl gas used for etching remains. The portion of the abnormal etching generated in this manner is liable to cause disconnection of the aluminum wiring portion, resulting in a problem of lowering the product yield. The occurrence of abnormal etching due to the relationship between the solution used for this wet processing and the wiring material or the material of the pixel electrode is theoretically
This can be avoided by changing the wiring material and the material of the pixel electrode.

[0004]

However, Al which is a wiring material is an indispensable material for wire bonding, and ITO is a transparent member having the lowest resistance and most stable at present. At present there is no suitable alternative material. Therefore, it is conceivable to avoid the above-mentioned abnormal etching by providing an interlayer insulating film between Al and ITO so as to prevent the ITO from being exposed. However, ITO is used as a hydrofluoric acid-based etchant for the interlayer insulating film. Has been exposed for a long time, and as a result, there has been a problem that the contact resistance is increased.

As means for solving such inconveniences, for example, Japanese Patent Application Laid-Open No. 58-178562 discloses a method in which ITO is formed after Al is provided, and damage to Al generated when etching ITO is avoided. A for
Although a technique for anodizing the surface of the wiring has been disclosed, this method tends to increase the thickness of the oxide film, thereby increasing the contact resistance between ITO and Al and writing electric charges to the liquid crystal element. There was a problem that it became difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a method of manufacturing a highly reliable active matrix panel which has few defects in aluminum wiring in a manufacturing process.
The purpose is to provide the law.

[0007]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The present invention has 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 constituting the liquid crystal element are made of aluminum and partially formed. In a method for manufacturing an active matrix panel in which is connected by wiring electrodes laminated on the transparent electrode,
It is characterized by including. After forming the transparent electrode
Depositing aluminum and removing the deposited aluminum surface
While irradiating with ultraviolet rays, the atmosphere of ozone generated by this irradiation
Exposing the aluminum to the surface of the aluminum
After forming the oxide film, wet etching
Thereby, the aluminum layer is formed in a desired shape.

[0008]

According to the method of the present invention, ultraviolet irradiation and ozone atmosphere
An oxide film is formed by exposure to air, so it is thin and dense
Aluminum oxide film can be formed, leading to oxidation.
Subsequently, wet etching can be performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an active matrix panel and a method of manufacturing the same according to the present invention will be described with reference to FIGS. Here, FIG. 1 is a longitudinal sectional view showing an embodiment of the active matrix panel according to the present invention, and FIG. 2 is a partially enlarged longitudinal 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 includes a pixel portion 2 made 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 portion 2 as a basic unit, and these are arranged in a matrix form. Is shown in FIG. In the embodiment shown in FIG. 1, a connection pad 12 is provided on the left side of the TFT 3, and this connection pad 12 is connected to the wiring electrode 10 at a location not shown. The connection from the active matrix panel to the external circuit is made by connecting the wiring from the circuit (not shown). The oxide film 11 is formed on the upper surface of the connection pad 12 in the same manner as the wiring electrode 10.
Does not require special treatment for removal since wiring from an external circuit or the like is connected to the connection pad 12 when the connection pad 12 is connected by, for example, an ultrasonic welding method. It is.

In this embodiment, a gate electrode 4 is provided on an insulating substrate 1, and an 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.
Further, a part of the gate insulating film 6, that is, the TFT
The active layer 7 and the channel protective layer 8
Are sequentially stacked, and an ohmic contact layer 9 is stacked so as to cover side edges of the active layer 7 and the channel protection layer 8. Further, on the active layer 7, an oxide film 11 as a layer composed of the wiring electrode 10 and the etching resistant member is sequentially laminated, and further, a protective film 13 is provided so as to cover the whole thereof. On the other hand, in the pixel section 2, a pixel electrode 14 is stacked on the gate insulating film 6. A part of the pixel electrode 14 is connected to the wiring electrode 1 described above.
The wiring electrode 10
Plays a role of a wiring electrode between the TFT 3 and the pixel electrode 14. The 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 a wiring electrode 10 made of aluminum as described later.
It functions as a layer made of an etching-resistant member in which etching does not progress due to an electrochemical reaction generated between the pixel electrode 14 and ITO.

Next, a manufacturing process of the active matrix panel having the above-described configuration will be described. First, a metal member (for example, aluminum) forming the gate electrode 4 is deposited and patterned by an evaporation method or the like on the insulating substrate 1 to form the gate electrode 4. Subsequently, the gate electrode 4 is formed. An anodic oxide film 5 is formed on the upper surface of the gate 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, for example, a plasma CVD method. The back surface is exposed from the lower side of FIG. 1 to pattern the SiNx forming the channel protection layer 8 to form the channel protection layer 8 and the a-Si: H forming the active layer 7 is self-aligned. The active layer 7 is obtained by forming.

Subsequently, n + a-Si forming an ohmic contact layer 9 is deposited and patterned to form source / drain regions 7a and 7b. Subsequently, the pixel electrode 14 is formed by depositing and patterning ITO forming the pixel electrode 14. Next, Al (aluminum) is deposited to a thickness of about 1 μm by sputtering. Then, after the Al film is formed, UV light (ultraviolet light) is irradiated and O3
The Al surface 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 surface of the aluminum grain 20 forming the wiring electrode 10 at the junction between the two is surely covered (see FIG. 2). In addition to preventing the Al surface from acting as an electrode in the wet treatment of
And acts as a barrier for abnormal etching caused by the battery formed between the first and second cells.

After that, the wiring electrode 10 is formed by patterning Al by wet etching, followed by depositing SiNx to be the protective film 13 by plasma CVD, and patterning the connection pad 12 portion. Thus, the protective layer 13 is formed to complete the active matrix panel. In this embodiment, the oxide film 11 is formed on the Al surface by irradiating the surface of the Al with UV light and exposing the Al in the resulting O3. However, the present invention is not limited to this method. In an atmosphere containing treatment or oxygen 2
A method of performing heat treatment at about 00 degrees may be used. Also,
The member forming the wiring electrode 10 is S in place of aluminum.
An aluminum alloy containing i, Ti, Cu or the like may be used. Although the wiring electrode 10 and the pixel electrode 14 are directly joined, the wiring electrode 10 made of aluminum is used.
A layer made of Mo (molybdenum) may be provided between the wiring electrode 10 and the pixel electrode 14 made of ITO to lower the contact resistance between the wiring electrode 10 and the pixel electrode 14.

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 denoted by the same reference numerals, and the description thereof will be omitted. The following description will focus on the differences. In the second embodiment, an oxide film is formed on the surface of a wiring electrode made of Al in the first embodiment, but an etching protection film 15 made of Mo is provided on the surface of a wiring electrode made of Al. Is different from the first embodiment. Where A
Mo layered on top of l forms a battery locally between Al and ITO, and acts as a barrier against abnormal etching caused by the battery.

Next, a description will be given of a manufacturing process of the active matrix panel having the above-described configuration, focusing on differences from the first embodiment. That is, also in the second embodiment, the manufacturing process up to the formation of the pixel electrode 14 is as follows.
This is the same as in the first embodiment shown in FIG. After the pixel electrode 14 is formed, A
l, Mo in the order of about 1 μm Al and about 500 Mo
Angstrom film is deposited. Where M
In the deposition of o, the same etchant as that used for the deposition of Al is diverted as it is, and is continuously etched and patterned to form the wiring electrode 10 and the etching protection film 15. Thereafter, SiNx forming the protective film 13 is deposited by the plasma CVD method, and the connection pad 1 is formed.
The protective film 13 is formed by patterning the portion 2. 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 material forming the etching protection film 15 is not limited to Mo, and the aluminum of the wiring electrode 10 and the I
Of course, other members may be used as long as they can alleviate the contact potential difference generated with the TO or suppress the reaction. Specifically, for example, Ta, W, etc. are suitable as substitutes for Mo.

In the above two embodiments,
Although an active matrix panel having a TFT made of a-Si has been described as an example, the present invention is not limited to the active matrix panel having the structure of the above-described embodiment, but has a structure in which Al and ITO are in direct contact. The present invention can be applied to any active matrix panel having.

According to the present invention, ozone is generated by irradiating ultraviolet rays to the surface of aluminum, which is a wiring electrode in contact with ITO, and a dense oxide film is formed on the aluminum surface by exposing the aluminum to the atmosphere. As a result, the aluminum surface is protected, so that in the wet treatment when patterning aluminum, there is no erosion of the aluminum pinhole and ITO, which have conventionally occurred, and therefore, As a result, the product yield is improved and the reliability is improved.

[0019]

According to the method of the present invention, ultraviolet irradiation and ozone
An oxide film by exposing in an atmosphere
Can form a dense aluminum oxide film
To be able to perform wet etching
So there is no effect on the element characteristics due to heating,
This has the effect of increasing production efficiency.

[Brief description of the drawings]

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

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

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

FIG. 4 is a longitudinal 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 protection film

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1362 G02F 1/13 101 H01L 29/78

Claims (1)

(57) [Claims] 1. A liquid crystal element and a plurality of switching elements connected to the liquid crystal element, wherein the switching element and a transparent electrode made of indium tin oxide constituting 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 is deposited after the formation of the transparent electrode.
Irradiating the aluminum surface with ultraviolet light
The aluminum in the atmosphere of ozone generated by the
To form an oxide film on the aluminum surface
The aluminum layer by wet etching
Active mat characterized by being formed into a desired shape
Rix panel manufacturing method.