JP2002123185A - Method for manufacturing transparent electrode substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent faulty removal of resist and popping of resist when the resist is removed. SOLUTION: A method for manufacturing a transparent electrode substrate includes a stage for forming an ITO film 2 on a glass substrate 1, a stage for forming a resist mask 3 partially on the ITO film 2, a stage for dry-etching the ITO film 2 using halogen gas (I) or halide gas (HI), a stage for washing the glass substrate 1 using pure water and a stage for performing high frequency plasma treatment 6 to the resist mask 3 using the gas containing at least oxygen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a transparent electrode substrate having a transparent electrode provided on a substrate, such as an active matrix substrate in a liquid crystal display device, in which a transparent conductive film and a photoresist are formed. Later, the present invention relates to a method for manufacturing a transparent electrode substrate by high-frequency plasma processing.

[0002]

2. Description of the Related Art In an active matrix substrate used in a liquid crystal display device, a transparent electrode having a predetermined shape is formed on a glass substrate. Such a transparent electrode substrate,
For example, In ₂ O ₃ —SnO ₂ formed on a glass substrate
It is manufactured by etching a transparent conductive film made of an (ITO) film by a wet etching method or a dry etching method.

Japanese Patent Application Laid-Open No. 58-120780 discloses that after a metal layer is formed by a plating means on an ITO film made of a metal oxide such as tin oxide or indium oxide formed on a substrate, an acid is added to the metal layer. Let the solution work, ITO
A wet etching method for removing a film is disclosed. In this case, a mixed solution of sulfuric acid, phosphoric acid, and acetic acid is used as the acid solution for dissolving the metal layer.

In recent years, with the miniaturization of patterns formed on a substrate, a dry etching method which is excellent in fine workability has been adopted. For example, Japanese Patent Application Laid-Open No. 8-971
No. 90 discloses a dry etching method for etching an ITO film on a substrate using high frequency plasma of an etching gas containing a halogen gas or a halide gas. In this case, at least one gas selected from the group consisting of bromine, hydrogen bromide, iodine, and hydrogen iodide is used as a gas used for the etching treatment.

[0005] In the case where an ITO film which is a transparent conductive film is subjected to dry etching treatment, the resist is exploded when the resist is removed after doping impurity atoms by ion implantation into a semiconductor substrate or the like.
g) It is known that a popping phenomenon occurs when the resist provided on the ITO film is removed similarly to the phenomenon.

First, the popping phenomenon that occurs when the resist is removed after doping the semiconductor substrate with impurity atoms will be described.

FIGS. 2A to 2D are schematic sectional views showing respective steps of resist removal at the time of impurity doping by ion implantation.

As shown in FIG. 2A, when the substrate 21 is doped with an impurity, first, a photoresist is applied to a portion of the substrate 21 where the impurity doping is not to be performed, and is covered with a pattern mask. After that, a trapezoidal resist mask 23 whose cross section is almost rectangular is formed by photolithography or the like.

Thereafter, as shown in FIG. 2B, an impurity dopant 27 is implanted on the substrate 21 by using an ion implantation method. At this time, P (phosphorus), B (boron), As (arsenic), etc. of the impurity dopant 27, which is a conductive impurity, are chemically bonded to a resin component near the surface of the resist mask 23, and the contact surface with the substrate 21 is formed. Resist mask 23 other than
Becomes a very hard altered layer 28. The resin component inside the resist mask 23 to which the impurity dopant 27 which is a conductive impurity does not reach is the resist mask 23.
The initial state at the time of formation is maintained, and is called a non-altered layer 28a.

When the ion implantation is completed, as shown in FIG. 2C, ashing, which is etching of the resist, is performed using oxygen plasma 26, and the resist mask 23 is removed. Resist mask 2 using oxygen plasma 26
In the ashing method of No. 3, the altered layer 28, which is the surface layer of the resist mask 23, is destroyed by using the impact of active oxygen ions in the oxygen plasma 26, and the active oxygen ions and the resin components inside the resist mask 23 are destroyed. The resist mask 23 is removed by utilizing the oxidation reaction with.

The resist mask 2 is formed by the oxygen plasma 26.
When the ashing of No. 3 is performed, the plasma-converted oxygen ions react with P (phosphorus), B (boron), As (arsenic), etc. of the impurity dopant 27 which is a conductive impurity implanted in the resist mask 23. , P (phosphorus), B (boron), As (arsenic) and the like are generated. In particular, P (phosphorus), B (boron), and As (arsenic) generated by performing ashing using oxygen plasma 26 on the resist mask 23 in which the impurity dopant 27 is ion-implanted at a high dose at a high concentration. ) Has a problem that it is difficult to volatilize and remains as a residue on the substrate 21. Further, if the temperature of the substrate 21 is increased by the irradiation of the oxygen plasma 26 before the altered layer 28 of the resist mask 23 is completely removed, the volatile components in the resin in the non-altered layer 28a of the resist mask 23 become gaseous. Therefore, the inside of the non-altered layer 28a in the resist mask 23 expands.

In this case, the deteriorated layer 28 covering the non-degraded layer 28a of the resist mask 23 has a dense and gas-tight hermetic structure. As shown in FIG. 2D, when the pressure of the expanded gas 29 in the non-altered layer 28a of the resist mask 23 increases, the resist explosion occurs due to the popping phenomenon that the altered layer 28 of the resist mask 23 is broken and scattered. Occurs. And resist mask 2
If the altered layer piece 30 of the altered layer 28 in 3 is scattered due to the resist explosion, the altered layer piece 30 may become particles (foreign particle) and adhere to the substrate 21.
If particles adhere to the substrate 21, the reliability of the substrate 21 may be reduced. For this purpose, it is necessary to remove particles attached to the substrate 21, but in this case, there is a problem that production efficiency is reduced.

[0013]

The resist popping phenomenon at the time of removing the resist after doping the substrate with the impurity is caused by the transparent conductive layer formed on the glass substrate even when the transparent electrode substrate is manufactured. I, a permeable membrane
There is a problem that a similar resist popping phenomenon occurs in the dry etching process of the TO film.

FIGS. 3 (a) to 3 (d) each show a transparent conductive film I which is formed when a transparent electrode substrate is manufactured.
It is a schematic sectional drawing which shows each process of the resist removal in the dry etching process of a TO film | membrane.

When manufacturing a transparent electrode substrate, FIG.
As shown in (a), first, an ITO film 32, which is a transparent conductive film serving as an electrode pattern, is formed on a glass substrate 31, a photoresist is applied on the ITO film 32, and after covering with a pattern mask. Then, a trapezoidal resist mask 33 having a substantially rectangular cross section is formed by photolithography or the like.

Thereafter, as shown in FIG.
Dry etching is performed on the film 32 using an etching gas 34 to form an electrode pattern. When dry etching is performed on the ITO film 32 on which the resist mask 33 is formed on the glass substrate 31 by using the etching gas 34, a reaction product 35 generated by a chemical reaction between the ITO film 32 and the etching gas 34 becomes The resist mask 33 is attached again to the surface other than the contact surface with the glass substrate 31. still,
The resin component inside the surface layer to which the reaction product 35 adheres maintains the initial state when the resist mask 33 is formed, and is called a non-denatured resist 35a.

When the electrode pattern of the ITO film 32 is formed by the resist mask 33 on the glass substrate 31, FIG.
As shown in (c), ashing, which is etching of a resist, is performed using oxygen plasma 36, and the resist mask 33 is removed. The reaction product 35 re-adhered to the surface of the resist mask 33 is not generally removed by ashing using oxygen plasma 36 used for removing the resist. Therefore, the reaction product 35 of the resist mask 33
The inside of the surface layer to which is adhered is a non-denatured resist 35a.
Therefore, when the temperature of the substrate 31 is increased by the irradiation of the oxygen plasma 36, the volatile component in the resin in the non-altered resist 35a of the resist mask 33 is gasified, and the non-altered resist 35a in the resist mask 33 is gasified. The inside expands.

When the irradiation of the oxygen plasma 36 is continued, the temperature of the substrate 31 continues to rise, so that FIG.
As shown in FIG.
Within 5a, the pressure of the expanded gas 39 increases, and a popping phenomenon due to resist explosion occurs, in which the reaction product 35 on the surface of the resist mask 33 is broken and scattered. Then, the reaction product 35 on the surface of the resist mask 33 causes the resist mask 3
3 are scattered, the resist mask 3
The reaction product pieces 37 of No. 3 are particles (foreign matter fine particles)
And adhere to the glass substrate 31. If particles adhere between the electrode patterns, they may cause a short circuit, etc.
This may cause a decrease in the reliability of the transparent electrode substrate. For this,
It is necessary to remove particles attached to the glass substrate 31, but in that case, production efficiency is reduced.

An object of the present invention is to solve such a problem, and an object of the present invention is to provide a method for manufacturing a transparent electrode substrate capable of preventing a failure in removing a resist and a resist explosion at the time of removing the resist. is there.

[0020]

According to the present invention, there is provided a method for manufacturing a transparent electrode substrate, comprising the steps of: forming a transparent conductive film on a substrate;
A step of partially forming a photosensitive resin film on the transparent conductive film, a step of dry-etching the transparent conductive film using a halogen gas or a halide gas, and a step of cleaning the substrate with a cleaning liquid; Performing a high-frequency plasma treatment using a gas containing at least oxygen for the photosensitive resin film.

The transparent conductive film is made of In ₂ O ₃ -SnO.
₂ (ITO) film.

The cleaning liquid is pure water.

The halogen gas or the halide gas is at least one of bromine, hydrogen bromide, iodine and hydrogen iodide.

[0024]

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

When manufacturing a transparent electrode substrate, FIG.
In removing the resist in the dry etching process of the ITO film as the transparent conductive film shown in (a) to (d), oxygen plasma treatment was performed after dry etching was performed using an etching gas containing a halide. Even in this case, since resist explosion occurs at the resist mask, resist particles adhere to the glass substrate and cannot be completely removed.

Therefore, an SiO ₂ film is formed on the glass substrate instead of the ITO film, a photoresist is applied on the SiO ₂ film, and after covering with a pattern mask, a resist mask is formed by photolithography or the like. Similarly to the case of the ITO film, when dry etching was performed using an etching gas containing a halide, and then ashing was performed by oxygen plasma treatment, the resist mask could be completely removed. Accordingly, when dry etching is performed using an etching gas containing a halogen gas or a halide gas, the film to be etched is SnO ₂
It has been found that if the film is a film other than the ITO film containing In ₂ O ₃ as a main component, resist explosion and resist removal failure do not occur. Explosion of resist during dry etching using an etching gas containing a halogen gas or a halide gas is a problem peculiar to the ITO film.

Therefore, the defective resist removal due to ashing is not caused by the fact that the resist mask cannot be removed due to the damage to the resist mask during the dry etching and the resist cannot be removed, but the reaction between the halide gas and the ITO film. It is considered that the removal of the resist by ashing in the oxygen plasma treatment was hindered because the product was deposited on the surface of the resist mask.

Further, an ITO film is formed on a glass substrate,
In the case where a resist mask is formed on the ITO film, dry etching is performed using a halide gas of hydrogen iodide (HI), and the surface of the resist mask is subjected to secondary ion mass spectrometry (SIMS:
Secondion Ion Mass Spectro
When analyzed by (scopy), In was detected in addition to the resist material. ITO film and hydrogen iodide (HI)
Are considered to be SnI ₄ and InI _3. However, since the vapor pressure of SnI ₄ is higher than that of InI ₃ and the gas is easily exhausted, the surface of the resist mask has InI 4
Only ₃ have been deposited.

Based on these results, the ITO film pattern
Doping for completely removing the resist mask after
I deposited on the surface of the resist mask during light etching
nI _ThreeBy removing In compounds such as
It is thought that the outbreak of the incident would be prevented. The present invention
It is based on such knowledge.

FIGS. 1A to 1E are schematic sectional views showing each step of a dry etching process in the method for manufacturing a transparent electrode substrate according to the present invention.

First, as shown in FIG. 1A, an ITO film 2 which is a transparent conductive film is formed on a glass substrate 1 by a sputtering method. The sputtering conditions are as follows: the sputtering target is In ₂ O ₃ —SnO ₂ , the component ratio of Ar and O ₂ : Ar / O ₂ = 99% / 1%, and the pressure is 10 mTo.
rr, sputtering power: 700 W, substrate temperature: 300
° C, and the thickness of the ITO film 2 is 1500 °.

Next, as shown in FIG. 1B, a photoresist is applied on the ITO film 2 to a thickness of 1.0 μm.
After covering with a pattern mask, a trapezoidal resist mask 3 whose cross section is nearly rectangular is formed by an exposure phenomenon such as photolithography.

Thereafter, as shown in FIG. 1C, dry etching is performed by using a mixed gas of hydrogen iodide (HI) and argon (Ar) as an etching gas 4 in a parallel plate type dry etching apparatus. I do. At this time, ITO
A reaction product 5 generated by a chemical reaction between the film 2 and the etching gas 4 is reattached to the surface of the resist mask 3 other than the surface in contact with the glass substrate 1. The resin component inside the surface layer to which the reaction product 5 has adhered maintains the initial state when the resist mask 3 was formed. Etching gas 4
Is added for the purpose of improving the etching rate, and the same applies when another inert gas such as helium (He) is added. The effect is obtained. Also, there is no particular problem in removing the resist mask 3 even when no inert gas is added.

Further, after the dry etching, ITO
When the glass substrate 1 on which the film 2 and the resist mask 3 are formed is immersed in pure water for 5 minutes, the glass substrate 1 is generated by a chemical reaction between the ITO film 2 and the etching gas 4 during dry etching. As shown in FIG. 1D, the highly water-soluble InI ₃ , which is the reaction product 5 re-adhered to the surface other than the surface in contact with the glass substrate 1, is easily removed by pure water washing as shown in FIG.

After cleaning the glass substrate 1 on which the ITO film 2 and the resist mask 3 are formed with pure water,
The glass substrate 1 on which the ITO film 2 and the resist mask 3 are formed is dried by a spin dryer, and an ashing process is performed by a barrel type ashing device which is a plasma processing device using an oxygen gas, as shown in FIG. Such a transparent electrode substrate was obtained. The ashing conditions were as follows: oxygen gas flow rate: 350 sccm, Power: 1000 W,
Pressure: 500 mTorr, ashing time: 60 minutes. After the ashing process is completed, the surface of the glass substrate 1 where the resist mask 3 has been formed is subjected to surface observation and optical SEM observation using an optical microscope.
It was confirmed that there was no resist or other deposits on the surface of the O film 2 and the region to be etched.

For comparison with such a method for manufacturing a transparent electrode substrate of the present invention, a glass substrate on which an ITO film 2 and a resist mask 3 which have been subjected to dry etching shown in FIG. On the sample No. 1, an ashing process was immediately performed by a barrel type ashing device, which is a plasma processing device using oxygen gas, after the completion of the dry etching. Ashing conditions are as follows: oxygen gas flow rate: 350 s
ccm, Power: 1000W, Pressure: 500mTo
rr, ashing time: 60 minutes. After the ashing is completed, the surface of the glass substrate 1 where the resist mask 3 is formed is observed with an optical microscope for surface observation and SEM observation. As shown in FIG. Also, a portion where the opening 7 was formed in the resist mask 3 due to the resist explosion due to the popping phenomenon was confirmed.

As described above, the resist mask used for forming the pattern of the ITO film, which is a transparent conductive film, on the glass substrate is formed at the time of dry etching by performing pure water washing after completion of dry etching. And
Since the reaction product redeposited on the surface of the resist mask is dissolved, the reaction product is completely removed by ashing using oxygen gas.

In the embodiment of the present invention, hydrogen iodide (HI) is used as an etching gas for dry etching. However, even when a bromine-based (Br) gas is used as an etching gas, The reaction product InBr is water-soluble and has the same effect as when hydrogen iodide (HI) is used. The etching gas for dry etching is a gas of hydrogen iodide, iodine, hydrogen bromide or bromine. Any of them may be used.

In the embodiment of the present invention, the resist mask is ashed by using oxygen gas. However, the same effect can be obtained by adding N ₂ gas and H ₂ gas to oxygen gas.

[0040]

As described above, according to the method for manufacturing a transparent electrode substrate of the present invention, a transparent conductive film in which a photoresist is partially laminated on a glass substrate is formed, and a halogen gas or a halide gas is discharged. After the dry etching using the glass substrate, the reaction product remaining on the photoresist during the dry etching is removed by washing the glass substrate. Thereafter, high-frequency plasma treatment is performed using a gas containing at least oxygen in the photoresist. There is no possibility that resist explosion will occur even if it is performed. Therefore, a highly reliable transparent electrode substrate can be efficiently manufactured.

[Brief description of the drawings]

FIGS. 1A to 1E are schematic cross-sectional views of respective steps of a method for forming a transparent conductive film on a glass substrate according to an embodiment of the present invention. (F) is a schematic cross-sectional view when an ashing process is performed immediately after dry etching for comparison.

FIGS. 2A to 2D are schematic cross-sectional views showing respective steps when ion implantation is performed on a substrate.

FIGS. 3A to 3D are schematic cross-sectional views of respective steps of a conventional method for forming a transparent conductive film on a glass substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 ITO film 3 Resist mask 4 Etching gas 5 Reaction product 6 Oxygen plasma 7 Opening 21 Substrate 23 Resist mask 26 Oxygen plasma 27 Impurity dopant 28 Altered layer 28a non-altered layer 29 Expanded gas 30 Altered layer piece 31 Glass Substrate 32 ITO film 33 Resist mask 34 Etching gas 35 Reaction product 35a Non-altered resist 36 Oxygen plasma 37 Reaction product piece 39 Expanded gas

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01B 13/00 503 H01B 13/00 503D 5G435 F-term (Reference) 2H090 JB02 JC07 JC09 JC19 LA01 2H092 HA04 MA15 MA19 MA22 MA37 NA16 NA27 4K029 AA09 BA10 BA15 BA45 BA47 BA50 BC09 CA05 GA02 5C094 AA43 AA44 BA03 BA43 CA19 EA04 EA05 EA07 EB02 5G323 CA01 5G435 AA17 BB12 CC09 KK10 KK09 KK10

Claims (4)

[Claims] 1. A step of forming a transparent conductive film on a substrate, a step of partially forming a photosensitive resin film on the transparent conductive film, and applying a halogen gas or a halide gas to the transparent conductive film. A transparent electrode, comprising: a step of performing dry etching using a cleaning liquid; a step of cleaning the substrate with a cleaning liquid; and a step of performing high-frequency plasma processing using a gas containing at least oxygen in the photosensitive resin film. Substrate manufacturing method. 2. The method according to claim 1, wherein the transparent conductive film is made of In ₂ O ₃ —SnO _2.
The method for producing a transparent electrode substrate according to claim 1, wherein the transparent electrode substrate is an (ITO) film. 3. The method according to claim 1, wherein the cleaning liquid is pure water. 4. The method according to claim 1, wherein the halogen gas or the halide gas is at least one of bromine, hydrogen bromide, iodine, and hydrogen iodide.