JPH117848A - Method for forming conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the production line unit process time and improve the production yield when forming a transparent conductive film. SOLUTION: A photoresist 11 is applied onto an insulating base 11 and patterned so as to be left in the part other than a desired ITO(indium tin oxide) pattern, and an ITO 12 is applied to the resulting base by sputtering to uniformly form a film on the base. The ITO 12 is wet-etched to lift off the resist 11, whereby the patterning of the ITO 12 is completed. Since the resist is preliminarily patterned in the part requiring no ITO 12, the etching residue, even if present on the surface of the insulating base 10, can be lifted off and removed together with the resist, so that no residue is generated in the part requiring no ITO 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a transparent conductive film used as an electrode wiring material of an electronic device such as a liquid crystal display device, a solar cell, a PDP (plasma display), and an EL (electroluminescence) element.

[0002]

2. Description of the Related Art In general, a transparent conductive film is used for an electronic device, for example, a pixel electrode or a signal wiring of a liquid crystal display device.
xide) Membrane is mainly used.

[0003] For example, the sputtering method is mainly used for forming the ITO film in terms of uniform film thickness distribution, easy control of light transmittance and electric resistivity, and application of a low-temperature process. It is used for Further, for example, in order to pattern an electrode wiring of a liquid crystal display device, it is general to perform wet etching on the formed ITO.

FIG. 5 shows that in the manufacture of an electronic device,
FIG. 3 is a cross-sectional view for explaining a flow of forming a wiring pattern using a TO film. In FIG. 5A, the wafer or the insulating substrate 100 processed up to the required manufacturing process
On top of this, an ITO film is uniformly formed by a sputtering method.

Next, in FIG. 5B, after a photoresist 102 is applied, it is patterned into a desired shape.

[0006] Next, in FIG.
101 is removed by etching with an etching solution. At this time, when performing wet etching of the ITO, etching is performed for a longer time than the etching time calculated at the time of design so that no etching residue is generated in consideration of the film quality unevenness of the ITO generated at the time of film formation. Generally, so-called over-etching is performed.

Then, a photoresist 102 (FIG. 5)
When (c)) is peeled and removed, as shown in FIG.
The patterning of 101 is completed.

[0008] ITO film formation and patterning have been performed by the above process.

[0009]

As described above, for example, the electrode wiring of a liquid crystal display device is made of ITO as a transparent conductive film.
In the case of forming by, the generation of etching residues was prevented by performing over-etching. However, in a portion of the formed ITO where a step is formed due to, for example, covering a lower wiring, the etchant penetrates deeply into the step of the ITO by performing over-etching, and as a result, unnecessary etching is performed. May enter and cause disconnection.

In particular, the adhesion between ITO and the resist formed thereon is poor, and when an etchant infiltrates between them, or when the ITO film is formed, a mouth hole (depending on the conditions for forming the ITO film) is formed in the step. Depending on the growth direction or crystal size of the ITO crystal grains, ITO may not be able to completely cover the step portion of the base.
(It refers to the state where there is a hole between TOs.)
In the case where (a)) occurs, the etching may proceed more than necessary due to over-etching, and a step disconnection (side etching or side shift) may occur (FIG. 6A). That is, when a mouse hole as shown in FIG. 6B is formed in the step, the etching solution may reach the mouse hole before the etching is completed. As a result, the etching solution penetrates into the ITO portion to be left through the mouth hole and the etching proceeds unnecessarily, so that a disconnection failure is likely to occur.

Also, ITO originally has a property in which the film properties are easily changed depending on the film forming conditions, and the properties of the film are changed depending on the power, gas pressure, substrate temperature, atmosphere gas state, etc. in the sputtering process. Needless to say, even when a splash occurs during the film forming process or a foreign substance or stain is present on the underlayer, an amorphous portion in which the ITO film quality is minutely and locally changed sometimes remains on the substrate.

When a local change in the film quality of ITO occurs, the etching rate is partially deviated, so that a minute etching residue remains even in a portion where it is not necessary to form ITO due to insufficient circulation of the etching solution. I was The occurrence of such etching residues may cause defects such as peeling of a thin film formed thereon and short-circuiting with an upper layer wiring. For example, in a liquid crystal display device, there is a problem that image display quality is deteriorated. Had a point.

The present invention relates to the formation and patterning of a transparent conductive film, and it is an object of the present invention to provide a method capable of eliminating a residue and reducing shape defects due to etching at a step, and requiring no complicated steps. .

Although the configuration is different from that of the present invention, a technique for solving the same problem is disclosed in JP-A-6-280055, which will be described below. According to the above publication,
Only a SnO ₂ film is intended as a transparent conductive film. To solve the problem due to the etching residue, a metal film having a desired pattern is formed on the substrate surface, and a transparent conductive film is formed so as to cover the metal film. After that, the transparent conductive film on the metal film is peeled off by melting away the metal film with an etchant. However, according to this method, when a transparent conductive film having a fine pattern is to be formed, sputtering, a photolithography process, and an etching process are required when patterning a metal film, which complicates the process, and reduces the manufacturing cost and work efficiency. There was a defect in point.
Further, since patterning of the metal film requires two steps of a photolithography step and an etching step, there has been a problem that the incidence of shape defects in the transparent conductive film increases.

[0015]

According to a method of forming a conductive film of the present invention, a step of forming a pattern forming means on a substrate except for a desired conductive film forming part, and covering the pattern forming means. The method includes a step of forming a conductive film, a step of performing wet etching on the conductive film, and a step of removing the pattern forming unit, thereby achieving the above object.

It is desirable that the etching rate of the conductive film on the pattern forming means is higher than the etching rate of the conductive film in a portion where the pattern forming means is not provided.

Further, the method may include a step of forming a mask having a predetermined shape after forming the conductive film.

The operation of the above configuration will be described below.

According to the first aspect of the present invention, since a pattern forming means made of, for example, a resist or the like is previously formed in a portion where the conductive film is not formed, even if an etching residue is generated, the pattern is formed after the etching. By stripping the forming means, the residue is completely lifted off.

According to the second aspect of the present invention, since the etching rate of the conductive film in the portion to be removed by etching is set faster than that in the remaining conductive film, the etching time can be reduced as compared with the conventional case. Becomes Further, the over-etching time can be shortened. Therefore, it is possible to reduce the amount of the etching solution permeated into the portion to be left, and it is possible to reduce the disconnection failure due to the penetration of the etching at the step portion.

According to the third aspect of the present invention, the thickness of the conductive film to be formed can be reduced by forming a mask on the conductive film formed by the method of the first aspect. Manufacturing time can be reduced.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 shows a manufacturing process diagram for explaining a method of forming a conductive film of the present embodiment. In the present embodiment, an example in which ITO is used as the transparent conductive film will be described. The description is given below.

First, as shown in FIG. 1A, a photoresist 11 which is an organic film dissolved in, for example, an organic amine-based stripping solution or a phenolbenzene-based stripping solution is formed on an insulating substrate 10 as a pattern forming means by etching. And then patterning. As a patterning method,
A known photo process can be used.

Next, as shown in FIG.
2 is uniformly formed on the substrate surface by a sputtering method.

After that, wet etching is performed as shown in FIG. HCl, F as etchant
A general one such as a mixed solution of eCl ₃ can be used. At this time, the ITO 12a on the resist 11 (FIG. 1)
(B)) shows ITO12b having no resist in the lower layer (FIG. 1)
Since the etching rate is much faster than (b)),
The etching time can be greatly reduced. The reason why the etching rate differs depending on the location is that the crystallinity of the formed ITO strongly depends on the physical properties of the lower layer. I on organic film such as general photoresist
The etching rate of the TO can be eight times or more than the etching rate of the ITO on the inorganic film such as glass or SiN _x. This is because the form (shape) of the ITO crystal formed differs depending on the base. Specifically, ITO on the organic film is ITO on glass or SiN.
This is because the crystals are gathered more sparsely than in the case, the etchant easily permeates between the grains, and the etching rate is increased. Therefore, the etching time can be made shorter than before, and the over-etching time can be shortened. Therefore, it is possible to reduce the entry of the etching liquid into the portion to be left, and it is possible to reduce the occurrence of a shape defect due to the entry of the etching into the step portion or the like.

After the etching, the resist is stripped (dissolved and removed) using an organic amine-based or phenol-benzene-based stripping solution, thereby completing the patterning as shown in FIG. At this time, since a resist is previously patterned in a portion not requiring the ITO 12, even if an etching residue is generated on the surface of the insulating substrate 10, the etching residue is completely lifted off at the same time as the resist is peeled off. No residue is generated in portions that do not require ITO12.

In this embodiment, the transparent conductive film is made of I
Although TO was used, the present invention is not limited to this, and may be applied to SnO ₂ or the like.

(Embodiment 2) Another embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, an active matrix substrate of a liquid crystal display device in which picture element electrodes are formed of ITO will be described.

FIG. 2 is a schematic plan view of an active matrix substrate using a TFT as a switching element.
FIG. 3 shows an AA sectional view (left side in the drawing) and a BB sectional view (right side in the drawing) in FIG.
Hereinafter, description will be made with reference to FIGS. Note that, in the following description, FIG.

First, a gate electrode 21 and a gate wiring 32 are formed on an insulating substrate 20 as shown in FIG. Glass is used as the insulating substrate 20, and A
1, Mo, Ta and the like were laminated by a sputtering method, and then patterned to form a gate electrode 21. Note that an insulating film such as Ta ₂ O ₅ or SiO ₂ may be formed in advance on the surface of the glass substrate as a base coat film.

Next, an insulating film is laminated on the gate electrode 21 and the entire image display area. In this embodiment, the plasma C
The gate insulating film 22 was formed by laminating a 3000 nm SiN _x film by the VD method. At this time, in order to further enhance the insulating property, the gate electrode is previously anodized to form a first gate insulating film, and then a second insulating film is formed by a CVD method as a second insulating film.
It may be coated with iN _x or the like.

Next, as shown in FIG. 3B, the intrinsic semiconductor (ia-Si) and SiN _x are deposited on the gate insulating film 2.
2 and 400 ° and 200 ° by the CVD method, respectively.
0Å laminated. Subsequently, the SiN _x was patterned to form an etching stopper 23.

Next, an n ⁺ -type amorphous silicon layer (n ⁺ a-Si) or microcrystalline silicon (n ⁺ -μc-Si) to which phosphorus has been added is plasma-
The layers are laminated by the method D. The n ⁺ -type amorphous silicon layer is provided for improving ohmic contact of a source or drain electrode to be subsequently laminated. Here, the intrinsic semiconductor and the n ⁺ -type amorphous silicon layer or the microcrystalline silicon previously formed were patterned to form the semiconductor layer 24 and the contact layer 25.

Subsequently, as shown in FIG. 3C, Ta, Ti, Al and the like were laminated by a sputtering method, and thereafter, patterning was performed to form a source electrode 26 and a drain electrode 27.

Next, as shown in FIG.
Photoresist 28 is applied to portions where O is not necessary to be formed.
Is applied and patterned. Subsequently, FIG.
After the ITO 29 is uniformly formed on the substrate surface by the sputtering method as described above, wet etching is performed as shown in FIG. HCl, FeCl as etchant
Common ones such as the mixed solution of ₃ can be used.

At this time, the ITO 29a on the resist 28
(FIG. 3 (e)) shows ITO29b without a resist in the lower layer.
Since the etching rate is much faster than (FIG. 3E), the etching time can be significantly reduced.
Specifically, for example, the etching rate of ITO on an organic film such as a general photoresist is, for example, glass or Si.
It may be eight times or more of the ITO etching rate on the inorganic film such as N _x. Therefore, the etching time can be made shorter than before, and the over-etching time can be shortened. As a result, the penetration of the etching solution into the portion to be left can be reduced, and the shape defect due to the penetration of the etching into the step portion or the like can be reduced.

Further, after the etching, the resist 28 is peeled off to complete the patterning as shown in FIG. 3 (g), thereby completing the picture element electrode 30. At this time, ITO
Since the resist is patterned in advance in portions that do not require, even if an etching residue is formed on the substrate surface, the residue is completely lifted off by removing the resist 29, so that ITO is required. No residue is generated in the portion where no treatment is performed.

Finally, although not shown, as the protective film 33, S
The active matrix substrate is completed by stacking and patterning iN _x by a CVD method.

(Embodiment 3) Following the step shown in FIG. 3E in Embodiment 2, a photoresist having a pattern similar to a desired ITO pattern is further formed on the formed ITO. Thereafter, when etching and resist peeling are performed, patterning can be performed without reducing etching of a necessary portion of ITO. That is, I
Since the portion where the TO is to be left is covered with the resist, the ITO in this portion is not exposed to the etchant, and the unnecessary etching is not performed.

(Embodiment 4) In Embodiments 2 and 3 described above, T formed by sputtering as a source electrode is used.
Although metals such as a, Ti, and Al are used, the source electrode and the drain electrode may be formed only of ITO. Note that the steps before FIG. 4A can be performed in the same manner as in FIGS. 3A to 3C described in the second embodiment, and a description thereof will be omitted.

In FIG. 4A, a photoresist 28 is applied to a portion not requiring ITO, and patterning is performed. Subsequently, after forming an ITO 29 by a sputtering method in FIG. 4B, etching is performed as shown in FIG. Further, the resist 28 is peeled off as shown in FIG.

In the etching step, since the etching rate of the ITO 29a on the resist 28 is much higher than that of the ITO 29b in the part without the resist, the etching and the resist peeling are performed without using a photomask again to complete the patterning of the ITO 29. , The source electrode 26, the source wiring 31, the drain electrode 27, and the picture element electrode 30 were completed.

Finally, although not shown, a protective film (SiN _x )
Are stacked by a CVD method and patterned to complete an active matrix type liquid crystal display panel.

[0044]

According to the present invention, in the patterning of an ITO thin film used for manufacturing an electronic device by etching, it is possible to form a portion of ITO to be removed as a film having a higher etching rate than other portions. It becomes possible. Therefore, the etching time can be reduced as compared with the conventional case, and the over-etching time can also be reduced. As a result, it is possible to reduce the amount of the etching solution permeating into the portion to be left, and to reduce the shape defect (disconnection defect) due to the penetration into the step portion or the like.

Since a resist is previously patterned in a portion that does not require ITO,
Even if a residue is formed, the residue is completely lifted off by stripping the resist after etching.
No residue is generated in portions that do not require TO.

As described above, according to the present invention, the production tact can be shortened, and the production yield can be further improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a method for manufacturing a transparent conductive film in Embodiment 1.

FIG. 2 is a plan view illustrating a configuration of an active matrix substrate according to a second embodiment.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing an active matrix substrate in Embodiment 2.

FIG. 4 is a sectional view illustrating a method for manufacturing an active matrix substrate according to a fourth embodiment.

FIG. 5 is a cross-sectional view illustrating a conventional method for forming a transparent conductive film.

FIG. 6 is a cross-sectional view showing a disconnection failure of a transparent conductive film.

[Explanation of symbols]

 10, 20, 100 Insulating substrate 11, 102 Photoresist 12, 29, 101 ITO 21 Gate electrode 22 Gate insulating film 23 Etching stopper 24 Semiconductor layer 25 Contact layer 26 Source electrode 27 Drain electrode 28 Resist 30 Pixel electrode 31 Source wiring 32 gate wiring 33 protective film

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01L 31/04 H01L 29/78 612C // G02F 1/1343 31/04 H

Claims (3)

[Claims] A step of forming a pattern forming means on a portion of the substrate other than a desired conductive film forming part; a step of forming a conductive film covering the pattern forming means; A method for forming a conductive film, comprising: a step of performing etching; and a step of removing the pattern forming unit. 2. The method for forming a conductive film according to claim 1, wherein an etching rate of the conductive film on the pattern forming means is higher than an etching rate of a part of the conductive film without the pattern forming means. 3. The method for forming a conductive film according to claim 1, further comprising a step of forming a mask having a predetermined shape after forming the conductive film.