WO2006075506A1

WO2006075506A1 - Transparent electrode and method for fabricating same

Info

Publication number: WO2006075506A1
Application number: PCT/JP2005/023700
Authority: WO
Inventors: Kazuyoshi Inoue; Nobuo Tanaka; Koki Yano
Original assignee: Idemitsu Kosan Co., Ltd.
Priority date: 2005-01-11
Filing date: 2005-12-26
Publication date: 2006-07-20
Also published as: TWI375099B; KR20070093098A; TW200641490A

Abstract

Disclosed is an indium-free transparent electrode which is excellent in alkali resistance, wet heat stability and etching properties. Specifically disclosed is a transparent electrode mainly containing zinc oxide and tin oxide wherein the taper angle at the edge portion of the electrode is 30-89˚. The ratio of zinc atoms to the total of zinc atoms and tin atoms in the transparent electrode (Zn/(Zn + Sn) atomic ratio) is preferably within the range of 0.5-0.9.

Description

Specification

Transparent electrode and manufacturing method thereof

Technical field

The present invention relates to a transparent electrode used for a thin display or the like. More specifically, the present invention relates to a transparent electrode mainly composed of zinc oxide and tin oxide, the electrode having a tapered end, and a method for manufacturing the electrode.

Background art

[0002] Liquid crystal display devices are considered promising among thin displays because they have features such as low power consumption and easy full colorization, and in recent years, development relating to enlargement of display screens has been active. Among them, the active matrix liquid crystal flat panel display that drives α-Si thin film transistors (TFTs) or p-Si TFTs as switching elements in a matrix for each pixel, and has a high definition of 800 x 600 pixels or more. Since the contrast ratio does not deteriorate even when the display is made, it is attracting attention as a flat display for high-performance color display.

In such an active matrix type liquid crystal flat display, a transparent electrode such as indium oxide-tin oxide (ITO) is used as a pixel electrode, and an A1-based alloy is used as a gate electrode and a source / drain electrode. Many use thin films. This is because the sheet resistance of ITO is low and the permeability is high, and A1 is easy to pattern and has low resistance and high adhesion.

Here, a configuration example of the TFT substrate will be described. Figure 4 shows a cross section near the Si TFT at the stage where pixel electrode pattern formation was completed in the liquid crystal flat panel display manufacturing process.

In FIG. 4, a gate electrode pattern 22 is formed on a translucent glass substrate 21, and then a plasma CVD method is used to form a SiN gate insulating film 23, an a_Si: H (i) film 24, and a channel protective film 25. And _{α 2} —Si: H (n) film 26 are continuously formed to form a desired shape pattern. Further, a metal film mainly composed of A1 is deposited by a vacuum evaporation method or a sputtering method, and a source electrode pattern 27 and a drain electrode pattern 28 are formed by a photolithography technique, and an a-Si TFT element portion is completed. In this example, a protective film 30 is formed. On this, an ITO film is deposited by a sputtering method to form a pixel electrode pattern 29 electrically connected to the source electrode 27 by a photolithography technique. The reason for depositing the film after the A1 film is to prevent deterioration of the electrical contact characteristics between the α-Si: film and the source and drain electrodes.

A1 is an indispensable material in the sense that it is inexpensive and has a low specific resistance to prevent deterioration of the display performance of the liquid crystal display due to increased resistance of the gate and source / drain electrode wiring.

[0006] In the above manufacturing process, after forming a source / drain electrode pattern mainly composed of A1, if the ITO pixel electrode pattern is processed with an HC1-HNO-H0 etching solution,

3 2

The problem that the A1 pattern elutes frequently occurred at the end of the process.

This is because A1 is also an HCl-HNO_H 2 O-based etchant, which is an ITO etchant.

3 2

It originates in having the property to melt | dissolve. HN ○ in the etchant is thin on the Al surface.

Three

A1 Oxide film is added to prevent the dissolution of A1. IT ○ The etching time of the film is long, or defects such as impurities and foreign matter in the A1 film mixed during A1 deposition. In the presence of A, the effect of oxidation of A1 by

Three

It is thought that it does not work. In addition, when A1 and ΙΤΟ are electrically joined together and immersed in a 2.38wt% aqueous solution of tetramethylammonium hydride oxide (ΤΜΑΗ), which is the resist image solution, A1 is eluted by the battery reaction. There is also the problem of doing.

[0007] In order to prevent such elution of A1, by making the ITO film amorphous, HC1-HNO

It is possible to increase the ITO / A1 etching rate ratio for -H 2 O-based etching solutions.

3 2

(For example, see Patent Document 1).

However, even if the ITO film is made amorphous, an HC1-HNO-H〇-based etchant is used.

3 2

Therefore, the elution of A1 was not completely prevented, and a high-definition liquid crystal display could not be realized.

[0008] With respect to this problem, patterning of the transparent electrode and pixel electrode made of indium oxide-zinc oxide on the A1 gate and source / drain electrode patterns is performed by using an oxalic acid-based etching solution. It has been proposed to make it easier (see eg patent document 2).

By the way, indium tin oxide (ITO), which is generally used as a transparent electrode Both indium oxide and zinc monoxide (IZO) are based on indium oxide. In recent years, the demand for indium has been increasing rapidly for thin display applications, and its price has soared. For this reason, there exists a problem that the price of the sputtering target used in order to produce a transparent electrode also rises.

For this reason, zinc oxide-based transparent conductive films that do not use indium oxide and tin oxide-based transparent conductive films have been proposed (see, for example, Non-Patent Document 1, Patent Documents 3 and 4). However, it is known that zinc oxide films are not practical because they are weak in acid and alkali solutions due to their properties. In addition, in the formation of zinc oxide, zinc oxide near the substrate has low crystallinity and the surface of the transparent conductive film has high crystallinity. Therefore, in the etching process, the film near the substrate is etched from the surface. There was a problem that the easily etched electrode became an inverted trapezoid (undercut).

On the other hand, tin oxide has a problem of being difficult to etch even with aqua regia (a mixed acid of nitric acid and hydrochloric acid), which is a strong acid, because chemical stability is too strong.

Patent Document 1: JP-A 63-184726

Patent Document 2: Japanese Patent Laid-Open No. 11 264995

Patent Document 3: Japanese Patent Laid-Open No. 6-293956

Patent Document 4: JP-A-9 35535

Non-Patent Document 1: Japan Society for the Promotion of Science Transparent Oxide Optical / Electronic Materials 166th Edition: Transparent Conductive Film Technology, Ohmsha (1999)

[0012] The present invention has been made in view of the above-mentioned problems, and is a transparent electrode that does not use indium, and has an object to provide a transparent electrode that is excellent in alkali resistance and wet heat stability and has excellent etching power. And

It is another object of the present invention to provide a method for producing a transparent electrode in which the electrode end is less likely to have an inverted trapezoidal shape (can be easily tapered).

Disclosure of the invention

[0013] The inventors of the present invention have made extensive studies in order to solve the above-mentioned problems. As a result, a transparent electrode is formed using a sputtering target mainly composed of zinc oxide's oxide, and the sputtering target is also used. When forming a transparent electrode using a predetermined etching solution As a result, it was found that the end of the electrode can be easily formed into a tapered shape, and the present invention has been completed.

According to the present invention, the following transparent electrode and the manufacturing method thereof can be provided.

1. A transparent electrode composed mainly of zinc oxide and tin oxide and having a taper angle of 30 to 89 degrees at the end of the electrode.

2. The transparent electrode according to 1, wherein the ratio of zinc atoms to the total amount of zinc atoms and tin atoms in the transparent electrode (ZnZ (Zn + Sn), atomic ratio) is 0.5 to 0.9.

3. A method for producing a transparent electrode, wherein a transparent conductive film containing zinc oxide and tin oxide as a main component is etched so that the taper angle of the electrode end is 30 to 89 degrees.

4. The method for producing a transparent electrode according to 3, wherein the ratio (ZnZ (Zn + Sn), atomic ratio) of zinc atoms to the total amount of zinc atoms and tin atoms in the transparent electrode is 0.5 to 0.9. .

5. The method for producing a transparent electrode according to 3 or 4, wherein a hydrohalic acid aqueous solution having a concentration power of wt% to 40 wt% is used for the plating.

6. Transparent conductive film composed mainly of zinc oxide and tin oxide, with the ratio of zinc atoms to the total amount of zinc atoms and tin atoms (Zn / (Zn + Sn), atomic ratio) being 0.5 to 0.9 A first step of forming a resist film, a second step of forming a resist film on the transparent conductive film, and using the resist film as a resist developer, a 1 to 5 wt% aqueous solution of tetramethylammonium hydride oxide. Then, the third step of patterning the temperature of the aqueous solution in a range of 20 to 50 ° C. and the transparent conductive film are etched using an aqueous solution having a hydrohalic acid concentration of 1 wt% to 40 wt%. And a fourth step of forming a transparent electrode having a taper angle of 30 to 89 degrees,

And a fifth step of stripping the resist film remaining on the transparent electrode using a resist stripping solution containing ethanolamine. The method for producing a transparent electrode according to any one of claims 3 to 5.

7. Transparent conductive film mainly composed of zinc oxide and tin oxide with a zinc atom ratio (Zn / (Zn + Sn), atomic ratio) to the total amount of zinc and tin atoms of 0.5 to 0.85 And etching the transparent conductive film using an aqueous solution having an oxalic acid concentration of 1 wt% to 10 wt% as an etchant and a temperature of the etchant in the range of 20 to 50 ° C. 4. The method for producing a transparent electrode according to 3, comprising a step of patterning.

8. A first step of forming a transparent conductive film mainly composed of zinc oxide and tin oxide, a second step of forming a resist film on the transparent conductive film, and a third step of patterning the resist film, Etching the transparent conductive film with a mixed solution of nitric acid, hydrochloric acid and water to remove the resist film remaining on the transparent electrode, and a fourth step of forming a transparent electrode having a taper angle of 30 to 89 degrees The method for producing a transparent electrode according to 3 or 4, comprising a fifth step.

9. The composition of the above mixed solution is a ternary system of nitric acid-monohydrochloric acid-water, in the ratio of nitric acid: hydrochloric acid: water (A) 2: 2: 96, (B) 2: 2: 96, (C) The method for producing a transparent electrode according to 8, wherein the transparent electrode is within a quadrilateral region surrounded by a composition point of 78: 2: 20 and (D) 78: 20: 2.

10. The method for producing a transparent electrode according to 8 or 9, wherein the temperature of the mixed solution of nitric acid: hydrochloric acid: water in the fourth step is 20 to 50 ° C.

11. The resist developer used in the third step is a 1 to 5 wt% aqueous solution of tetramethyl ammonium hydroxide, and the resist stripper used in the fifth step contains ethanolamine. The manufacturing method of the transparent electrode in any one of.

12. A method of etching a transparent conductive film mainly composed of zinc oxide and tin oxide using an aqueous oxalic acid solution.

13. The etching method according to 12, wherein the concentration of oxalic acid in the oxalic acid aqueous solution is 1 wt% to 10 wt%.

14. A method of etching a transparent conductive film mainly composed of zinc oxide and tin oxide using a mixed solution of nitric acid, hydrochloric acid and water.

15. The composition of the mixed solution of nitric acid, hydrochloric acid and water is the ratio of nitric acid: hydrochloric acid: water in a ternary system of nitric acid-hydrochloric acid-water (A) 2: 2: 96, (B) 2 The etching method according to 14, which is in a quadrilateral region surrounded by the composition points of: 2: 96, (C) 78: 2: 20 and (D) 78: 20: 2.

Since the transparent electrode of the present invention does not use indium, it is inexpensive regardless of the price fluctuation of indium. By using zinc oxide and tin oxide as the main components, it is possible to make the electrode excellent in alkali resistance and moist heat resistance. In addition, by using a predetermined etching solution, it is possible to prevent the end of the electrode from becoming an inverted trapezoid and to obtain an electrode controlled to have a constant taper angle.

Brief Description of Drawings

FIG. 1 is a cross-sectional view of a transparent electrode.

FIG. 2 is a diagram showing a production process of the transparent electrode of the present invention.

FIG. 3 is a diagram showing a composition region of a suitable mixed solution of nitric acid: hydrochloric acid: water in the present invention.

FIG. 4 is a diagram showing an example of a TFT substrate.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the transparent electrode of the present invention will be specifically described.

FIG. 1 is a cross-sectional view of the transparent electrode of the present invention.

The transparent electrode 11 of the present invention is formed on the substrate 10, mainly composed of zinc oxide and tin oxide, and has a taper angle (30) at the electrode end of 30 to 89 degrees.

“Mainly composed of zinc oxide and tin oxide” means that the proportion (atomic ratio) of zinc and tin oxide in the transparent electrode is 51% or more. In the present invention, the proportion of the oxide is preferably 75% or more, particularly preferably 90% or more.

[0018] Zinc and tin oxide forms include zinc oxide such as ZnO, SnO, SnO

2 Forms of tin oxide such as ZnSnO, Zn SnO, etc. Complex oxidation between zinc oxide and tin monoxide

3 2 4

Although there are physical forms, amorphous forms are preferred.

This amorphous transparent conductive film has excellent etching characteristics not found in zinc oxide-based transparent conductive films and tin oxide-based transparent conductive films. In other words, unlike zinc oxide-based transparent conductive films, the end of the electrode after etching does not easily have an inverted trapezoidal shape, and when the etching characteristics are poor as in the case of tin oxide, it is not possible.

[0019] The transparent electrode of the present invention has a taper angle of 30 to 89 degrees at the electrode end. When the taper angle is smaller than 30 degrees, the distance between the electrode edges becomes longer, and when the liquid crystal or organic EL is driven, the contrast between the pixel periphery and the inside may be different. If the taper angle exceeds 89 degrees, electrode cracking or peeling at the edge may occur, and in the case of liquid crystals, the alignment film may be defective, or in the case of organic EL, the counter electrode may be disconnected. [0020] The film thickness of the transparent conductive film (transparent electrode) is preferably 5 to 300 nm force S, more preferably 20 to 150 nm force S, and particularly preferably 30 to 80 nm. If the film thickness is less than 5 nm, the resistance value may be too high, and if it exceeds 300 nm, the taper angle of the electrode end after etching may not be within 30 to 89 degrees.

In the present invention, since the transparent conductive film mainly composed of zinc oxide and tin oxide described above is used, the taper angle of the transparent electrode can be controlled.

The taper angle is controlled by adjusting the composition, concentration, temperature, etc. of the etching solution used when etching the transparent conductive film. Specifically, an oxalic acid aqueous solution, a mixed solution of nitric acid / monochloric acid / water, or a hydrohalic acid aqueous solution can be used as an etching solution.

[0022] When an aqueous oxalic acid solution is used, the taper angle can be controlled by the concentration of the aqueous oxalic acid solution. Specifically, in order to reduce the taper angle, the concentration of the oxalic acid aqueous solution is adjusted to be low. Conversely, to increase the taper angle, the concentration of the oxalic acid aqueous solution is adjusted to be high.

In this case, the ratio of zinc atoms (Zn / (Zn + Sn), atomic ratio) to the total amount of zinc atoms and tin atoms in the transparent electrode is preferably 0.5 to 0.85. If Zn / (Zn + Sn) is greater than 0.85, control becomes difficult, the taper angle of the electrode end becomes 90 degrees or more, and side etching becomes too large, which may result in electrode thinning or disconnection. is there. In addition, the contact resistance between the transparent electrode and the anisotropic conductive film (ACF) connecting the external circuit may increase, and the contact resistance with the ACF may increase during the durability test (high temperature and high humidity).

On the other hand, if the Zn / (Zn + Sn) force is less than SO.5, the etching rate may decrease and etching may not be possible. Preferably, Zn / (Zn + Sn) is 0.5 to 0.8, and more preferably 0.7 to 0.8.

[0023] When using a mixed solution of nitric acid / hydrochloric acid / water as an etching solution, the taper angle can be controlled by adjusting the composition ratio of the mixed solution. Specifically, to reduce the taper angle, increase the ratio of hydrochloric acid. Conversely, to increase the taper angle, decrease the ratio of hydrochloric acid.

When etching with a mixed solution of nitric acid / hydrochloric acid / water, the ratio of zinc atoms to the total amount of zinc atoms and tin atoms in the transparent electrode (ZnZ (Zn + Sn), atomic ratio) is 0.5-0. 9 is preferred. The reason for this is the same as in the case of oxalic acid described above. More preferably, Zn / (Zn + Sn) is 0.55 to 0.85, and more preferably 0.57 to 0.8. Particularly preferably, it is 0.60 to 0.77, more preferably 0.64 to 0.74, and most preferably 0.64 to 0.69.

[0024] When a hydrohalic acid aqueous solution is used as the etching solution, the taper angle can be controlled by the concentration of the hydrohalic acid or the temperature of the hydrohalic acid aqueous solution. Specifically, to decrease the taper angle, lower the concentration of hydrohalic acid, or lower the temperature of the aqueous solution. Conversely, to increase the taper angle, increase the concentration of hydrohalic acid. What is necessary is just to raise the temperature of aqueous solution.

When etching with a hydrohalic acid aqueous solution, the ratio of zinc atoms to the total amount of zinc atoms and tin atoms in the transparent electrode (ZnZ (Zn + Sn), atomic ratio) is 0.5 to 0.9. It is preferable that The reason for this is the same as in the case of oxalic acid described above. More preferably ί, ∑11 / (211 + 311) to 0.52 to 0.7, more preferably ί, 0.55 to 0.67, particularly preferably 0.55 to 0.63. is there.

In the present invention, the transparent conductive film mainly composed of zinc oxide and tin oxide is preferably an amorphous film. If it is not an amorphous film, it is difficult to control the taper angle, and it may not be possible to keep it within 30 to 89 degrees.

The atomic ratio (Zn / (Zn + Sn), atomic ratio) is a value measured by ICP (high frequency inductively coupled plasma) analysis. Note that the ratio of atoms in the raw material of the sputtering target used for forming the transparent conductive film (transparent electrode) is substantially equal to the ratio of the atoms in the actually obtained transparent conductive film. Therefore, the atomic ratio [Zn / (Zn + Sn)] of the transparent conductive film can be controlled by adjusting the atomic ratio in the raw material of the sputtering target.

[0026] The transparent electrode of the present invention can be produced by etching and patterning a transparent conductive film having an amorphous conductive oxide composed mainly of zinc oxide and tin oxide. This will be described below with reference to the drawings.

FIG. 2 is a diagram showing a production process of the transparent electrode of the present invention. The manufacturing process mainly consists of forming a transparent conductive film (first step, Fig. 2 (a)), forming a resist film (second step, Fig. 2 (b)), and patterning the resist film (third step, Fig. 2). 2 (c)), etching of transparent conductive film (fourth process, Fig. 2 ( d)), peeling of the resist film on the transparent electrode (fifth step, Fig. 2 (e)).

[0028] (1) Formation of transparent conductive film

A transparent conductive film 11 ′ is formed on the substrate 10 on which the transparent electrode is to be formed.

As the substrate 10, a transparent resin plate such as a glass plate, polysulfone or polycarbonate which is a transparent substrate can be used.

Examples of the method for forming the transparent conductive film 11 ′ include vapor deposition, sputtering, CVD, spraying, and dipping. Of these, sputtering is preferably used.

Specifically, a sputtering target prepared and sintered using zinc oxide and tin oxide as main raw materials may be used. In order to make the formed transparent conductive film 11 ′ an amorphous transparent conductive film, the substrate temperature during sputtering is adjusted to 300 ° C. or lower, or hydrogen is added to the sputtering gas during sputtering (10νο1. / _ο or less).

Thus, by making the transparent conductive film 11 ′ amorphous, it becomes possible to easily etch with the above-described etching solution.

[0029] (2) Formation of transparent electrode

Subsequently, the transparent conductive film is etched and patterned into a desired electrode pattern. The patterning can be performed by a method usually used in this technical field, for example, photolithography. That is, a resist film 12 is formed on the transparent conductive film 11 ′ (FIG. 2 (b)), and the resist film 12 is patterned by exposure and development (FIG. 2 (c)). Thereafter, the transparent conductive film 11 ′ is etched using an etching solution to form a desired pattern. Finally, the resist film 12 remaining on the transparent electrode 11 is removed using a stripping solution (FIG. 2 (d)) to form a transparent electrode (FIG. 2 (e)).

In the present invention, it is preferable to use an aqueous oxalic acid solution, a mixed solution of nitric acid / monochloric acid / water, or an aqueous hydrohalic acid solution as an etching solution.

When an aqueous oxalic acid solution is used as an etching solution, the concentration of oxalic acid in the aqueous oxalic acid solution is preferably lwt% to 10wt%. If the oxalic acid concentration is less than 1 wt%, the etching rate is slow, and if it exceeds 10 wt%, which is not practical, oxalate crystals may be precipitated. More preferably, it is 2 wt% to 7 wt%, and particularly preferably 2 wt% to 5 wt%.

[0031] When a mixed solution of nitric acid-hydrochloric acid-water is used as an etching solution, The composition of the mixed solution is the ratio (volume ratio) of nitric acid: hydrochloric acid: water, (A) 2: 96: 2, (B) 2: 2: 96, (C) 78: 2: 20 and (D) 78 It is preferably within a quadrilateral region surrounded by the composition point of: 20: 2.

FIG. 3 shows a composition region of a suitable mixed solution of nitric acid, hydrochloric acid and water in the present invention. In FIG. 3, a quadrilateral area (shaded area) formed by the points (A) to (D) is a preferable range. Outside this range, the etching rate may be too fast or too slow, and the taper angle of the electrode may not fall within the range of 30 to 89 degrees. The composition of this mixed solution is the ratio of nitric acid: hydrochloric acid: water, (Α ') 4:48:48, (Β') 4: 8: 88, (C ') 78: 8: 14 and (D') It should be within the quadrilateral region surrounded by the composition point of 78:11:11. The power of this mixture solution is the ratio of nitric acid: hydrochloric acid: water, (A ") 6:47:47, (B ") 6: 8: 86, (C ,,) 50: 8: 42, and (D ,,) 50:25: It is particularly preferable to be within a quadrilateral region surrounded by composition points.

Nitric acid is normal concentrated nitric acid (concentration 60%, specific gravity 1.40), and hydrochloric acid is normal concentrated hydrochloric acid (concentration 35%, specific gravity 1.18).

[0032] When a hydrohalic acid aqueous solution is used as an etching solution, for example, HI, HBr, HC1, or HF can be used as the hydrohalic acid. Preferably, it is HC1, HI or HF.

The concentration of halohydonic acid in the aqueous hydrohalic acid solution is preferably lwt% to 40wt%. If the concentration of halogen hydrohydrogen acid is less than 1 wt%, the etching rate is slow and impractical, and if it exceeds 40 wt%, crystals of halogen hydrohydrogen salt may precipitate. More preferably, it is 2 wt% to 35 wt%, and particularly preferably 3 wt% to 15 wt%.

[0033] In the present invention, the use temperature of the etching solution during etching is preferably 20 to 50 ° C. If it is less than 20 ° C, the etching rate is slow and practical, and if it exceeds 50 ° C, the concentration of the etching solution may fluctuate due to evaporation of water, hydrochloric acid, etc., and it may be difficult to control the concentration of the solution. The temperature is preferably 25 ° C to 45 ° C, more preferably 30 ° C to 45 ° C.

[0034] It is preferable to use an aqueous solution of tetramethylammonium hydride oxide (TMAH) as the resist developer. If an alkaline component other than TMAH is used, the resist pattern There is a possibility that a shift or dissolution occurs and a serious trouble occurs in etching. Also,

When A1 and the transparent conductive film are electrically joined, battery reaction may occur when they come into contact with the electrolyte solution, requiring caution.

[0035] The concentration of TMAH is preferably: 5 to 5 wt%. If it is less than lwt%, resist development failure may occur, and the formed transparent electrode is easily short-circuited. If the concentration exceeds 5 wt%, the resist pattern may be thinned or peeled off, and the electrode pattern may be thinned or disconnected. Preferably, it is 2 to 4 wt%.

[0036] Ethanolamine-based amine is preferably used as the resist stripping solution. Examples of ethanolamine-based amines include monoethanolamine, diethanolamine, and triethanolamine, and diethanolamine is preferably used. An aqueous solution may be used, but a mixed solution with a polar solvent can also be used. Examples of such polar solvents include DMF, DMSO, NMP and the like.

The concentration of ethanolamine-based amine in the resist stripping solution is preferably 10 wt% to 60 wt%, particularly preferably 20 wt% to 40 wt%.

Note that it is not preferable to use an inorganic alkali such as NaOH or KOH as the stripping solution because the electrode surface may be melted and uneven.

[0037] The carrier mobility of the transparent electrode thus formed is preferably 10 cm ² / V'SEC or more. More preferably, it is 20 cm ² / V ′ SEC or more. In the case of TFT drive LCD, if it is less than 10 cm ² / V 'SEC, the response speed may become slow and the image quality of the liquid crystal may be degraded. Resistivity is lower rather is accordance, but in the case of TFT driving, the distance from the TFT element to LCD drive electrode end is not a problem if so very short 10- ² Omega cm base.

Carrier mobility is measured by the Hall measurement method (Fundia Po method).

[0038] In the transparent electrode of the present invention, a third metal can be added within a range that does not affect the carrier mobility. As the third metal, for example, a metal oxide having a small refractive index can be added for the purpose of improving the transmittance. Typical examples of these are MgO, B O, G

2 3 aO, GeO, etc.

2 3 2

In addition, an oxide having a small specific resistance can be added for the purpose of reducing the specific resistance of the transparent electrode. Typical examples of these include rhenium oxide, iridium oxide, and ruthenium oxide. Can be mentioned. However, since these heavy metal oxides may be colored and caution is required in the amount to be added, they should be added within a range that does not affect the transmittance.

[Example]

[0039] The present invention will be described more specifically with reference to examples.

[Preparation of sputtering target and substrate with transparent conductive film]

Production example 1

(1) Preparation of sputtering target

Zinc oxide powder (manufactured by Hakusui Tech Co., Ltd.) with an average particle size of 1 μm or less and tin oxide powder (manufactured by Mitsubishi Materials) with an average particle size of 1 μm or less are Zn / (Zn + Sn) = 0 79 (atomic ratio), mix in a resin pot, add pure water, and add hard Zr

Wet ball mill mixing was performed using a 2 roll mill. The mixing time was 20 hours.

The obtained mixed slurry was taken out, filtered, dried and granulated.

This granulated product was molded by a cold isostatic press while applying a pressure of 294 MPa (3 t / cm ² ).

[0040] This molded body was sintered as follows.

1500, in an atmosphere in which oxygen is introduced into the sintering furnace at a rate of 5 L / min per 0.1 lm ³ of the furnace volume. Sintered at C for 5 hours. In this case, 1000 ° C¾¾rl ° C / min, 1000 ~: 1500. C was heated at 3 ° C / min. Thereafter, the introduction of oxygen was stopped, and the temperature was decreased from 1500 ° C to 1300 ° C at 10 ° C / min. Then, in an atmosphere in which argon gas was introduced at a rate of 10 L / min per 0.1 lm ^{3 of the} furnace, the temperature was kept at 1300 ° C. for 3 hours and then allowed to cool. As a result, a zinc oxide / tin oxide-containing sintered body having a relative density of 90% or more was obtained.

[0041] The sputter surface of the obtained sintered body is polished with a cup grindstone, added to a diameter of 100 mm and a thickness of 5 mm, a backing plate is bonded using an indium alloy, and a sputtering target (sintered target) 1) was produced. The density of this target was 5.72 g / cm ³ .

[0042] In the target, it is preferable that tin oxide is dispersed, and in particular, it is substituted and dissolved in zinc oxide zinc site. That is, the form in which Sn is contained in the target may be a form in which Sn oxide such as SnO or SnO is dispersed, but ZnSnO, Zn SnO A form in which the zinc oxide is dispersed in the zinc oxide sintered body in the form of a composite oxide between zinc oxide and tin monoxide is preferable. This is because when Sn is dispersed at the atomic level in the zinc oxide sintered body, the discharge is stabilized in sputtering, and the resulting transparent conductive thin film has a low resistance.

[0043] The average diameter of the crystal particles obtained by the mapping image processing of Sn atom of EPMA (X-ray microanalyzer) of sintered compact target 1 was 3.87 m. Moreover, the Balta resistance (specific resistance) of Target 1 was 360 Ωcm, and a target capable of stable RF sputtering was obtained.

Table 1 shows the properties of the sintered compact target.

[0044] [Table 1]

(2) Production of transparent conductive film

The sintered compact target 1 was attached to the sputtering apparatus. Glass substrate (. Thickness lmm or 1 lmm) was moved into the apparatus, the ultimate vacuum: 5 X 10- ⁴ Pa, the film formation pressure: 0. LPA, substrate temperature: as 200 ° C, transparent substrate A conductive film (thickness lOOnm) was formed.

The atomic ratio [Zn / (Zn + Sn)], specific resistance, carrier mobility and light transmittance of this transparent conductive film were evaluated. The specific resistance and carrier-one (charge) mobility were obtained by Hall measurement. The light transmittance was measured for a light beam having a wavelength of 550 nm with a spectrophotometer. In addition, the atomic ratio (Zn / (Zn + Sn), atomic ratio) is ICP (high frequency inductive coupling bra Zuma) measured by analytical method,

Table 2 shows the measurement results.

[Table 2]

Light transmittance: Light transmittance at a wavelength of 5500 nm.

[0047] Production Example 2-7

Zinc oxide powder with an average particle size of 1 μm or less and tin oxide powder with an average particle size of 1 β m or less are used as raw material powder, and the ratio of zinc atoms to tin atoms is adjusted to the ratio shown in Table 1. Otherwise, a sputtering target (sintered body target 2-7) was produced in the same manner as in Production Example 1, and a substrate on which a transparent conductive film was formed was produced.

The diameter of the sputtering target was 152 mm and the thickness was 5 mm. Tables 1 and 2 show the properties of the sputtering target and the evaluation results of the transparent conductive film.

[0048] [Preparation of transparent electrode]

Example 1

On the transparent conductive film of the substrate with a transparent conductive film prepared in Production Example 1, a resist film was formed by spin coating using a resist solution (manufactured by Fuji Hunt, HPR204).

Next, the resist film was exposed and developed using a resist mask having a predetermined pattern. The developer is 2.8wt% tetramethylammonium hydride mouth oxide (TMAH) in water. The liquid was used.

Next, this substrate was treated with an aqueous oxalic acid solution as an etching solution, whereby the transparent conductive film was etched and the transparent electrode was patterned. The etching conditions were as follows: the concentration of the aqueous oxalic acid solution was 3.5 wt%, the temperature was 30 ° C., and etching was performed by dubbing. The etching rate under these conditions was evaluated.

In addition, the etching rate was evaluated when the use temperature of the oxalic acid aqueous solution was 40 ° C, and when the concentration of the oxalic acid aqueous solution was 5. Owt% and the use temperature was 35 ° C.

The results are shown in Table 3.

[0050] Finally, the resist film remaining on the transparent electrode was removed using a DMSO solution (30 wt%) of diethanolamine as a stripping solution. The conditions at this time were 40 ° C and 1 minute immersion.

Thus, a substrate on which transparent electrodes (width 90 μm, pitch 110 μm) were formed was produced. The taper angle of the electrode end of the obtained transparent electrode was measured by SEM observation. The results are shown in Table 3.

[0051] [Table 3]

[0052] Example 2-5 Comparative Example 1 2

A transparent electrode substrate was prepared and evaluated in the same manner as in Example 1 except that the substrate with a transparent conductive film prepared in Production Example 2-7 was used. The results are shown in Table 3.

[0053] Example 6 On the transparent conductive film of the substrate with the transparent conductive film prepared in Production Example 1, a resist film was formed by spin coating using a resist solution (manufactured by Fuji Huntne earth, HPR204).

Next, the resist film was exposed and developed using a resist mask having a predetermined pattern. A 2.8 wt% aqueous solution of tetramethyl ammonium hydroxide (TMAH) was used as the developer.

Next, the substrate is mixed with a mixed solution of nitric acid: hydrochloric acid: water (nitric acid: hydrochloric acid: water = etching solution) =

25:13:62), the transparent conductive film was etched and the transparent electrode was patterned. The liquid was used at a temperature of 30 ° C. and etched by dubbing.

Under these conditions, the etching rate was evaluated.

In addition, when the operating temperature of the above etching solution is 40 ° C, and using a mixed solution of nitric acid, hydrochloric acid and water (nitric acid: hydrochloric acid: water = 25: 25: 50), the operating temperature is 35 ° C. The etching speed was also evaluated.

The results are shown in Table 4.

[0055] Finally, the resist film remaining on the transparent electrode was removed using a DMSO solution of diethanolamine (30 wt%) as a stripping solution. The conditions at this time were 40 ° C and 1 minute immersion.

Thus, a substrate on which a transparent electrode (width 90 _β m, pitch 110 _β m) was formed was produced. The taper angle of the electrode end of the obtained transparent electrode was measured by SEM observation. The results are shown in Table 4.

[0056] [Table 4]

窗. ^ 1.0 ^ f ¥ A ¾1 L: n4.- ^ SU M¾room st i0577lo 34l 1 Etching rate used [AZ min] Taper angle With transparent conductive film (Bottom: Ratio of mixed solution S (HN0 ₃ : HC1: H ₂ 0) and operating temperature) [degree] substrate 25: 13:62 25: 13:62 25:25: 50

3 Ot: 40X 35 * C

Example 6 Production Example 1 30.000 25.000 85 Example 7 Production Example 2 2, 500 5.000 4,000 70 Example 8 Production Example 3 1.200 2.100

50 Example 9 Production Example 4 450 1,050 900 45 Example 10 Production Example 5 50 100 90 40 Comparative Example 3 Production Example 6 200.000 400.000 350, 000 140 Comparative Example 4 Production Example 7 ― ― ― 氺 Taper angle is mixed solution Ratio (HN0 ₃ : HC1: ¾0 o) Indicates the angle when o is 25:13:62 and the operating temperature is 30.

o

* Comparative example 4 is not etchable

o [0058] Example 11

On the transparent conductive film of the substrate with the transparent conductive film prepared in Production Example 1, a resist film was formed by spin coating using a resist solution (manufactured by Fuji Huntne earth, HPR204).

Next, the substrate was treated with an aqueous solution of 35% by weight of hydrogen chloride (HC1) as an etchant to etch the transparent conductive film and pattern the transparent electrode. The temperature at this time was 30 ° C., and etching was performed by datebing.

Under these conditions, the etching rate was evaluated.

The etching rate was also evaluated when the use temperature of the hydrochloric acid aqueous solution was 40 ° C, and when the concentration of the iodic acid aqueous solution was 5 wt% and the use temperature was 35 ° C.

The results are shown in Table 5.

[0060] Finally, the resist film remaining on the transparent electrode was removed using a DMSO solution of diethanolamine (30 wt%) as a stripping solution. The conditions at this time were 40 ° C and 1 minute immersion.

Thus, a substrate on which a transparent electrode (width 90 _β m, pitch 110 _β m) was formed was produced. The taper angle of the electrode end of the obtained transparent electrode was measured by SEM observation. The results are shown in Table 5.

[0061] [Table 5]

窗 SU0631

#Taper angle is HC1: 35wt% aqueous solution and operating temperature is 30 * Comparative Example 6 is not etchable

A connection test by the method (Tape Carrier Package) was conducted to evaluate the connection stability.

The TCP connection board was stored in an environment of 60 ° C and 90% RH, and the change in connection resistance with time was observed. The results are shown in Tables 6-8.

In Comparative Examples 2, 4 and 6, the connection resistance was evaluated for the substrate after the above-mentioned treatment for reference for the substrate with a transparent electrode.

[Table 6]

[Table 7] ZD / (Zn + Sn) TCP connection resistance [Ω]

[Atomic ratio]

Immediately after connection 240 hours 480 hours 960 hours 0066 Example 6 0. 79 4. 5 4. 9 5. 7 6. 6 Example 7 0. 75 4. 4 4. 8 5. 8 5. 8 Example 8 0. 70 4. 7 5. 2 5. 3 5. 4 Example 9 0. 67 4. 6 4. 8 5. 0 5. 1 Example 1 0 0. 55 4. 8 5. 2 5. 5 5.7 Comparative Example 3 0. 97 7. 1 20. 5 36. 5 1 30 Comparative Example 4 0. 40 5. 5 6. 2 6. 8 6. 7

Evaluation 2

On a glass substrate, and mounting a sputtering target of pure A1 on a sputtering apparatus, Itaru our vacuum: 5 X 10- ⁴ Pa, deposition pressure:. 0 LPA, substrate temperature: as room temperature, a thin film of A1 on a glass substrate (Thickness 200 nm) was formed.

Ten percent of the area of the obtained glass substrate was sealed with Kapton tape. On this substrate, a thin film of lOOnm thickness was formed at room temperature using Target 1-7 prepared in Production Example 1-7. Filmed. Thereafter, the Kapton tape was peeled off to produce a glass substrate with a laminated film in which the A1 film was partially exposed.

As a reference example, a laminated glass substrate with an ITO thin film formed on the A1 film was also produced.

[0068] These laminated glass-coated glass substrates were immersed in a 2.4 wt% aqueous solution of TMAH (20 ° C) for 2 minutes, and dissolution of the A1 film was observed. The results are shown in Table 9.

[0069] [Table 9]

[0070] Even when a glass substrate on which only a pure A1 film was formed was immersed in this aqueous solution, dissolution of the A1 layer was not observed. Therefore, it was confirmed that the battery reaction occurred due to the laminated structure of A1 / transparent conductive film in the case where dissolution of A1 was observed in this evaluation.

[0071] Rating 3

Add 10 vol% of water to the glass with a thin film of lOOnm obtained in Production Example 1 in a mixed solution of 30 vol% diethanolamine and 70 vol% dimethylsulfoxide (DMSO) as a resist remover at 45 ° C. Immerse for 5 minutes. Thereafter, the surface of the thin film was observed with a scanning electron microscope (SEM). As a result, unevenness and surface roughness were not observed.

On the other hand, as a result of performing the same operation using the glass with a thin film of lOOnm obtained in Production Example 6, irregularities and roughness of the surface were observed on the surface of the thin film, which is not suitable as an electrode for liquid crystal or organic EL. It was confirmed that. [0072] Rating 4

Using the substrate obtained by laminating the transparent conductive film and A1 film of Production Example 17 on a glass substrate, the transparent conductive film and A1 film are each in the form of a fine line with a line width of 50 μm, and the A1 fine line and the transparent conductive fine line are orthogonal to each other. (The intersection of both thin wires is in a laminated state). The contact resistance at the laminated interface was measured by the Keno Levin probe method. The results are shown in Table 10.

[0073] [Table 10]

Industrial applicability

The transparent electrode of the present invention is inexpensive because it does not use indium. Further, the electrode end portion having good etching characteristics can be formed in a tapered shape. Therefore, it is suitable as a transparent electrode used in thin displays such as liquid crystal display devices, organic electroluminescence display devices, and plasma displays.

Claims

The scope of the claims

[1] A transparent electrode mainly composed of zinc oxide and tin oxide and having a taper angle of 30 to 89 degrees at the end of the electrode.

[2] Ratio of zinc atoms to the total amount of zinc atoms and tin atoms in the transparent electrode (ZnZ (

2. The transparent electrode according to claim 1, wherein the atomic ratio) is 0.5 to 0.9.

[3] A transparent conductive film containing zinc oxide and tin oxide as the main component has a taper angle of 30 at the end of the electrode.

A method for producing a transparent electrode, which is etched to be -89 degrees.

[4] Ratio of zinc atoms to the total amount of zinc atoms and tin atoms in the transparent electrode (Zn / (

4. The method for producing a transparent electrode according to claim 3, wherein the Zn + Sn) and the atomic ratio) are 0.5 to 0.9.

5. The method for producing a transparent electrode according to claim 3 or 4, wherein a hydrohalic acid aqueous solution having a concentration power of Slwt% to 40wt% is used for the etching.

[6] Transparent conductive mainly composed of zinc oxide and tin oxide with a zinc atom ratio (Zn / (Zn + Sn), atomic ratio) of 0.5 to 0.9 with respect to the total amount of zinc atoms and tin atoms A first step of forming a film;

A second step of forming a resist film on the transparent conductive film;

A third step of patterning the resist film using a 1 to 5 wt% aqueous solution of tetramethylammonium hydride oxide as a resist developer, and the temperature of the aqueous solution in the range of 20 to 50 ° C .;

Etching the transparent conductive film with an aqueous solution having a hydrohalic acid concentration of lwt% to 40wt% to form a transparent electrode having a taper angle of 30 to 89 degrees; and on the transparent electrode The method for producing a transparent electrode according to any one of claims 3 to 5, further comprising a fifth step of stripping the remaining resist film using a resist stripping solution containing ethanolamine.

[7] Transparent conductivity mainly composed of zinc oxide and tin oxide with a zinc atom ratio (Zn / (Zn + Sn), atomic ratio) to the total amount of zinc and tin atoms of 0.5 to 0.85 Forming a film;

An aqueous solution having an oxalic acid concentration of 1 wt% to 10 wt% as an etching solution using the transparent conductive film The method for producing a transparent electrode according to claim 3, further comprising: etching and patterning an etching solution at a temperature of 20 to 50 ° C.

[8] a first step of forming a transparent conductive film mainly composed of zinc oxide and tin oxide;

A second step of forming a resist film on the transparent conductive film;

A third step of patterning the resist film;

Etching the transparent conductive film using a mixed solution of nitric acid, hydrochloric acid and water to form a transparent electrode having a taper angle of ¾ to 89 degrees; and

5. The method for producing a transparent electrode according to claim 3, further comprising a fifth step of peeling off the resist film remaining on the transparent electrode.

[9] The composition of the mixed solution is nitric acid-hydrochloric acid-water ternary system in the ratio of nitric acid: hydrochloric acid: water (A) 2: 2: 96, (B) 2: 2: The method for producing a transparent electrode according to claim 8, wherein the transparent electrode is in a quadrilateral region surrounded by the composition points of 96, (C) 78: 2: 20 and (D) 78: 20: 2.

10. The method for producing a transparent electrode according to claim 8 or 9, wherein the temperature of the mixed solution of nitric acid: hydrochloric acid: water in the fourth step is 20 to 50 ° C.

[11] The resist developer used in the third step is an aqueous solution of tetramethylammonium hydride:! To 5 wt%.

The method for producing a transparent electrode according to claim 8, wherein the resist stripping solution used in the fifth step contains ethanolamine.

[12] A method of etching a transparent conductive film mainly composed of zinc oxide and tin oxide using an aqueous oxalic acid solution.

13. The etching method according to claim 12, wherein the concentration power of oxalic acid in the aqueous oxalic acid solution is Slwt% ˜: 10 wt%.

[14] A method of etching a transparent conductive film mainly composed of zinc oxide and tin oxide using a mixed solution of nitric acid, hydrochloric acid and water.

[15] The composition of the mixed solution of nitric acid, hydrochloric acid and water has a ratio of nitric acid: hydrochloric acid: water in a ternary system of nitric acid-hydrochloric acid-water (A) 2: 2: 96, (B) 2 : 2: 96, (C) 78: 2: 20 and (D) 78

The etching method according to claim 14, wherein the etching method is in a quadrilateral region surrounded by a composition point of 20: 2.