JP3055289B2 - How to prevent deterioration of transparent electrode material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a liquid crystal display device,
In a resist developing step in the manufacture of a display device such as an electroluminescence display device or a photoelectric conversion device such as a contact image sensor, an electrically connected ITO (a transparent electrode material made of indium oxide and tin oxide; indium;・ Tin oxide) and Al or Al alloy are simultaneously exposed to a developing solution or the like.
The present invention relates to a method for preventing O and the like from being deteriorated by an electrochemical reaction.

[0002]

2. Description of the Related Art FIG. 5 shows a method of processing an electrode disclosed in Japanese Patent Application Laid-Open No. 63-140088, which is a method of processing an electrode by photoetching an electric element using two or more kinds of electrode materials. In order to prevent the solution used for the electrode from simultaneously contacting multiple electrodes made of different electrode materials, remove the electrode made of one electrode material beforehand except for the contact part with the electrode made of the other electrode material to be patterned. A method for processing an electrode, which is characterized by performing photo-processing after coating with a film, will be described.

[0003] The patent publication discloses that the electrode material is I
An example in which TO and Al are deposited on a glass substrate is shown.
In FIG. 5, first, as shown in FIG. 5A, a pattern of an ITO film 2 is formed on a glass substrate 1 as an electrode, and then, as shown in FIG. The part which does not need to be laminated with the Al electrode, and which is to be isolated from the processing liquid such as the etchant, is used as the first resist.
Coated with layer 13.

[0005] Thereafter, as shown in FIG. 5 (c), an Al film 4 is deposited as an electrode by vapor deposition, sputtering or the like, and then, as shown in FIG. 1
The pattern No. 4 is produced by photolithography.
At this time, as shown in FIG.
When the overlapping portion 15 of the layer 13 and the second resist layer 14 is provided, the separation between the ITO film 2 and a processing liquid such as an etchant can be more reliably performed.

The element shown in FIG. 5D is immersed in an Al etchant, and unnecessary Al is removed as shown in FIG. 5E to form an electrode pattern of the Al film 4. At this time, since only the Al film 4 is in contact with the etchant and the ITO film 2 is not in contact, no battery is formed between the ITO film 2 and the Al film 4. Finally, by removing the first resist layer 13 and the second resist layer 14 with a resist remover,
As shown in FIG. 5F, an ITO film 2 is formed on a glass substrate 1.
And an electrode pattern using two kinds of electrode materials of the Al film 4.

[0006]

In the conventional electrode processing method, when etching unnecessary Al, the first resist is used.
If there is a defect such as a pinhole which leads to the ITO film 2 in the layer 13, the second resist layer 14, and the Al film 4, the ITO film 2
And the Al film 4 are simultaneously exposed to the Al etchant, and
In the process of completely removing the resist first layer 13 and the resist second layer 14 from FIG. 5E to FIG. 5F, the ITO film 2 and the Al film 4 are simultaneously exposed to the stripper, and A
A battery is formed between the first and second films 4.

As a result, there is a problem that the ITO film 2 is deteriorated due to corrosion of the ITO film 2 by an electrochemical reaction. The phenomenon that the lower layer ITO is deteriorated by the generation of pinholes due to the dissolution reaction of Al is also described in Sharp Technical Report, No. 44 (1990), pp. 31-36. Since pattern dimensional accuracy is required with the increase in the density of electrode patterns in a display element, the need for measures to prevent the deterioration of ITO electrodes is increasing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems.
It is an object of the present invention to provide a method for preventing the deterioration of a transparent electrode material that can prevent the deterioration of ITO or the like even when the structure is electrically connected to 1 or Al alloy even when they are simultaneously exposed to an electrolytic solution.

[0009]

According to the method for preventing deterioration of a transparent electrode material of the present invention, in a structure in which a transparent electrode material is electrically connected to a metal (I), a metal (II) different from the metal (I) is used. ) Is electrically connected, immersed in high-temperature water, and then the structure is immersed in an electrolytic solution.

[0010]

According to the method for preventing the deterioration of the transparent electrode material according to the present invention, the metal (metal) is maintained so that the potential of the transparent electrode material in the electrolytic solution is maintained at a higher (noble) potential than the potential at which the deterioration proceeds rapidly. Since the metal (II) is further electrically connected to I) and immersed in high-temperature water and the structure is immersed in the electrolyte, the transparent electrode material and the metal (I) are simultaneously exposed to the electrolyte. However, as long as the metal (II) is exposed to the electrolyte, the deterioration of the transparent electrode material can be prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a method for preventing deterioration of a transparent electrode material according to the present invention will be described. First, in order to investigate the degradation mechanism of ITO, electrochemical measurement in an electrolytic solution was performed. Note that the potentials shown below are values expressed using an Ag / AgCl electrode as a reference electrode.

FIG. 4 shows a cathodic polarization curve of ITO in tetramethylammonium hydroxide. A peak of current is seen around -1.45V,
The ITO rapidly turns brown and is easily dissolved.

By the way, for example, when the same area of ITO and Al is electrically connected and immersed in tetramethylammonium hydroxide, the potential of ITO is -1.93.
V, and ITO turns brown. Also, ITO, A
The electric potentials when each of them were individually immersed in the electrolytic solution were near -0.15 and -1.93 V, respectively. Therefore,
By electrically connecting ITO and Al, ITO
Is lowered to the vicinity of the potential of Al lower than the above -1.45V, and as a result, ITO deteriorates.

Therefore, in order to prevent the deterioration of the ITO, the potential of the ITO must be maintained at a higher (noble) potential than the potential at which the deterioration proceeds rapidly (-1.45 V in the above example). I understood.

Therefore, as a result of repeated experimental studies, in a structure in which the transparent electrode material and the metal (I) are electrically connected, a metal (II) different from the metal (I) is electrically connected to cause a high temperature. After immersion in water, the structure is immersed in electrolyte.
It was confirmed that the deterioration could prevent the deterioration of the transparent electrode material. This is because the potential of the transparent electrode material in the electrolytic solution can be maintained at a higher (noble) potential than the potential at which the deterioration proceeds rapidly.

The transparent electrode material used in the method for preventing deterioration of the present invention is, for example, ITO, and the metal (I) is, for example, Al, Al—Si, Al—C.
u, Al-Nb, Al-Au, Al-Ag, Al-P
d, Al-Ru, Al-Si-Cu, Al-Cu-M
n, Al-Mn-Si, Al-Pd-Si and other Al alloys. Examples of the metal (II) include C
o, Fe, Ir, Ni, Pd, Pt, Re, Rh, W,
Mo and alloys containing these metals as main components are mentioned, and at least one of them is used.

The high-temperature water in which the structure is immersed may be a transparent electrode material, a metal (I) and the type of electrolyte, and the area ratio of the transparent electrode material exposed to the electrolyte to metal (I) and metal (II). Depending on the condition, a condition that can maintain the potential of the transparent electrode material in the electrolytic solution at a higher (noble) potential than the potential at which the deterioration rapidly proceeds is selected.

For example, ITO is used as a transparent electrode material, and Al, Al-Si, Al-Cu, Al-N is used as a metal (I).
b, Al-Au, Al-Ag, Al-Pd, Al-R
u, Al-Si-Cu, Al-Cu-Mn, Al-Mn
When using Al alloys such as -Si, Al-Pd-Si and immersing them in an electrolyte (tetramethylammonium hydroxide) having a pH of 13.5, ITO and Al or Al alloy and metal exposed to the electrolyte are exposed. Assuming that the area ratio of (II) is 2: 2: 1, as the metal (II), Co,
Fe, Ir, Ni, Pd, Pt, Re, Rh, W, Mo
And at least one of alloys containing these metals as main components
The seed is used , and 100 ° C. × 10 minutes is adopted as a condition for immersion in high-temperature water.

To give a specific example, an area ratio of 2: 1 and 100
Al (metal (I)) and N immersed in high-temperature water at 10 ° C for 10 minutes
The electric potential of Ni is 0.80 V when i (metal (II)) is electrically connected and simultaneously immersed in an electrolytic solution (tetramethylammonium hydroxide). Further, the potential of Ni when using Al-Si-Cu instead of Al is -0.50V. The potential of these Nis is higher than the potential (-1.45 V) at which the degradation of ITO proceeds rapidly.
The same can be said for metals (II) other than Ni.

By the way, the potential of ITO alone is -0.15
V. Therefore, Al or Al-Si, Al-C
u, Al-Nb, Al-Au, Al-Ag, Al-P
d, Al-Ru, Al-Si-Cu, Al-Cu-M
Regardless of the area ratio of ITO to Al alloy such as n, Al-Mn-Si, Al-Pd-Si or metal (II), ITO, Al or the Al alloy and metal (II) were simultaneously connected. In this case, the potential of ITO in the electrolyte does not become -1.45 V or less. Therefore,
Deterioration of ITO can be prevented.

An embodiment of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. A first example of a method for preventing ITO deterioration will be described with reference to FIG. In FIG. 1A, 1 is a glass substrate, 2 is an ITO film as a transparent electrode material, 3 is a metal (II) film, for example, a Ni film in this example, and 4 is A
1 film. The materials 2 to 4 are sequentially deposited on the glass substrate 1 in this order by a vapor deposition method, a sputtering method, or the like, as shown in FIG. Covering and removing unnecessary Al by dry etching to expose the surface of the Ni film 3 (FIG. 1).
(B)).

Next, the mask (not shown) is removed, and 10
After immersion in high-temperature water at 0 ° C. for 10 minutes, a resist film 5 is selectively applied and formed on the Al film 4 using a mask (not shown) (FIG. 1C). After exposing the resist film 5 using a photomask, the resist film 5 is subjected to a developing process using an electrolytic solution (tetramethylammonium hydroxide) for 2 minutes, and then A is exposed.
A wiring mask pattern of a resist film 5 is formed on the l film 4 (FIG. 1D). Thereafter, unnecessary Al of the Al film 4 is dry-etched, and the resist film 5 used as a mask is removed. An Al wiring or the like is manufactured (FIG. 1E).

In the photolithography process,
For example, if the area ratio between the Al film 4 and the Ni film 3 exposed to the electrolytic solution is 2: 1, the ITO film 2 is formed in the Al film 4 and the Ni film 3 when the resist film 5 is developed. Even if a defect (for example, a pinhole) exists, the ITO film 2 at that portion does not deteriorate.

After the Al wiring or the like is formed, the glass substrate 1 or the like may be cut as shown by the dotted line in FIG.

In this example, Al is used as the wiring material, but instead of Al , Al—Si, Al—Cu, Al
-Nb, Al-Au, Al-Ag, Al-Pd, Al-
Ru, Al-Si-Cu, Al-Cu-Mn, Al-M
Even if an Al alloy such as n-Si or Al-Pd-Si is used, Ni is effective in preventing the deterioration of ITO. Also, Ni
Also serves to prevent Al from diffusing into ITO. Therefore, Ni is effective as a layer having two roles of preventing deterioration of ITO and preventing diffusion of Al into ITO.

The same function can be achieved by using a metal (II) other than Ni. Further, although not shown in the figure, the metal (II) may be multi-layered, such as by sequentially laminating Ni and W on ITO.

Embodiment 2 FIG. A second example of a method for preventing ITO deterioration will be described with reference to FIG. FIG. 2 is a process sectional view showing one embodiment of a process for manufacturing a display element using the deterioration prevention method of the present invention. In FIG. 2A, 1 is a glass substrate,
Reference numeral 2 denotes an ITO film as a transparent electrode material, 6 denotes a metal (III) film, and in this example, a Cr film and 4 denotes an Al film. First, materials indicated by reference numerals 2, 6, and 4 are sequentially deposited on the glass substrate 1 in this order by a vapor deposition method, a sputtering method, or the like, and a necessary portion of the Al film 4 is covered with a mask (not shown), and dry etching is performed. Unnecessary portions of the Al film 4 and the Cr film 6 are removed to partially expose the ITO film 2 (FIG. 2B).

Next, as the metal (II) film, for example, a Ni film 3
Is selectively deposited on the ITO film 2 by a vapor deposition method, a sputtering method, or the like (FIG. 2C), a mask (not shown) on the Al film 4 is removed, and immersed in 100 ° C. high-temperature water for 10 minutes. A resist film 5 is selectively applied and formed on the Al film 4 by using a mask which is not used (FIG. 2D). Next, after exposing the resist film 5 using a photomask, the resist film 5 is formed on the Al film 4 through a development process for 2 minutes using an electrolytic solution (tetramethylammonium hydroxide).
Is formed (FIG. 2E). Al
The film 4 is dry-etched to remove unnecessary Al to produce an Al wiring or the like (FIG. 2 (f)). The metal (III) used in this example is formed to prevent Al from diffusing into ITO.

In the photolithography process,
At the time of developing the resist film 5, A
Even if a defect (for example, a pinhole) leading to the ITO film 2 exists in the l film 4 or the Cr film 6, the area ratio between the Al film 4 and the Ni film 3 exposed to the electrolytic solution is set to 2: 1. The ITO does not deteriorate if manufactured in advance.

In the second embodiment, when Ni is not used, the effect of preventing the deterioration of ITO is smaller than when Ni is used. However, when metal (III) such as Cr is used as shown in FIG. 2, it is effective in preventing Al from diffusing into ITO. Therefore, even if metal (III) such as Cr is used, as long as Cr and Ni are electrically connected, I
This is effective in preventing TO deterioration.

In this example, Al is used as a wiring material, but Al-Si, Al-Cu, Al
-Nb, Al-Au, Al-Ag, Al-Pd, Al-
Ru, Al-Si-Cu, Al-Cu-Mn, Al-M
Even if an Al alloy such as n-Si or Al-Pd-Si is used, Ni is effective in preventing the deterioration of ITO.

Embodiment 3 FIG. A third example of a method for preventing ITO deterioration will be described with reference to FIG. FIG. 3 is a process sectional view showing one embodiment of a process of manufacturing a display element using the deterioration prevention method of the present invention. In FIG. 3A, 1 is a glass substrate,
2 is an ITO film as a transparent electrode material, 6 is a metal (III) film, a Cr film in this example, 3 is a metal (II) film, and N in this example.
The i film 4 is an Al film. First, the materials denoted by reference numerals 2, 6, 3, and 4 are sequentially deposited on the glass substrate 1 in this order by an evaporation method, a sputtering method, or the like (FIG. 3A). After this,
A necessary portion of the Al film 4 is covered with a mask (not shown), and an unnecessary portion of the Al film 4 is removed by dry etching to expose a part of the Ni film 3 (FIG. 3B).

Next, the mask (not shown) is removed, and 10
After being immersed in high-temperature water of 0 ° C. for 10 minutes, a resist film 5 is selectively applied and formed on the Al film 4 using a mask (not shown) (FIG. 3C). After exposing the resist film 5 using a photomask, the resist film 5 is subjected to a developing process using an electrolytic solution (tetramethylammonium hydroxide) for 2 minutes, and then A is exposed.
A wiring mask pattern of a resist film 5 is formed on the l film 4 (FIG. 3D), and unnecessary Al of the Al film 4 is dry-etched to produce an Al wiring or the like (FIG. 3E).

In the photolithography process, the Al film 4, Ni film 3, Cr
Even if a defect (for example, a pinhole) leading to the ITO film 2 exists in the film 6, the film 6 is prepared so that the area ratio between the Al film 4 and the Ni film 3 exposed to the electrolytic solution is 2: 1. Then, the ITO in that portion does not deteriorate.

In this example, Al is used as the wiring material, but instead of Al , Al—Si, Al—Cu, Al
-Nb, Al-Au, Al-Ag, Al-Pd, Al-
Ru, Al-Si-Cu, Al-Cu-Mn, Al-M
Even if an Al alloy such as n-Si or Al-Pd-Si is used, Ni is effective for preventing the deterioration of ITO. Although not shown, a metal (II) other than Ni may be used, or the metal (II) may be multi-layered, such as by sequentially laminating Ni and W on ITO.

[0037]

As described above, according to the present invention, a metal (II) different from the metal (I) is connected to the structure of the metal (I) electrically connected to the transparent electrode material to increase the temperature. After immersion in water, the structure was immersed in the electrolytic solution. Therefore, even if the transparent electrode material and the metal (I) were simultaneously exposed to the electrolytic solution, the metal (II) was exposed to the electrolytic solution. As long as there is an effect, the deterioration of the transparent electrode material can be prevented.

[Brief description of the drawings]

FIG. 1 is a process cross-sectional view showing one example of a manufacturing process of a display element using a method for preventing deterioration of a transparent electrode material according to Embodiment 1 of the present invention.

FIG. 2 is a process cross-sectional view showing one example of a manufacturing process of a display element using the method according to the second embodiment.

FIG. 3 is a process cross-sectional view showing one example of a manufacturing process of a display element using the method according to the third embodiment.

FIG. 4 is a diagram showing a cathode polarization curve of ITO.

FIG. 5 is a process cross-sectional view showing a manufacturing process of a conventional display element.

[Explanation of symbols]

 2 ITO film (transparent electrode material) 3 Ni film (metal (II)) 4 Al film (metal (I))

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-8212 (JP, A) JP-A-3-223719 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01B 13/00 503 C23F 1/02

Claims (2)

(57) [Claims] 1. In a structure in which a transparent electrode material and a metal (I) are electrically connected, a potential of the transparent electrode material is higher than a potential at which its deterioration rapidly progresses in an electrolytic solution. The structure is characterized in that a metal (II) different from the metal (I) is electrically connected to the structure and immersed in high-temperature water, and then the structure is immersed in an electrolytic solution. How to prevent deterioration of transparent electrode material. 2. The transparent electrode material is ITO, the metal (I) is Al or an Al alloy, and the metal (II) is
Co, Fe, Ir, Ni, Pd, Pt, Re, R
2. The method for preventing deterioration of a transparent electrode material according to claim 1, wherein at least one of h, W, Mo and an alloy mainly containing these metals is used.