# US 7,608,547 B2 · Etchant and method for fabricating liquid crystal display using the same

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- Number: US 7,608,547 B2
- Document ID: US7608547B2
- Status: Granted
- Kind: B2
- Application number: 11/486,477
- Filed: 2006-07-13
- Published: 2007-07-19
- Granted: 2009-10-27
- Earliest claimed: 2005-07-13
- Assignees: Samsung Electronics Co., Ltd.
- Inventors: Hong-sick Park; Shi-yul Kim; Jong-hyun Choung; Won-suk Shin
- Web page: https://patentgrep.com/patent/US7608547B2

## CPC

- G02F 1/13439: {characterised by their electrical, optical, physical properties; materials therefor; method of making}
- H10F 71/138: {Manufacture of transparent electrodes, e.g. transparent conductive oxides [TCO] or indium tin oxide [ITO] electrodes}
- H10F 77/244: {made of transparent conductive layers, e.g. transparent conductive oxide [TCO] layers}
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

Provided are an etchant used for a transparent conductive oxide layer and a method for fabricating a liquid crystal display (LCD) using the etchant. The etchant includes 2-5 wt % sulfuric acid, 0.02-10 wt % hydrogen sulfate of alkali metal, and deionized water as the remainder.

## Claims

### Claim 1

An etchant for a transparent conductive oxide layer comprising:
2-15 wt % sulfuric acid;
0.02-10 wt % hydrogen sulfate of an alkali metal; and deionized water as the remainder,
wherein the transparent conductive oxide layer is made of indium tin oxide (ITO) or indium zinc oxide (IZO).

### Claim 2 (depends on 1)

The etchant of claim 1, wherein the hydrogen sulfate of an alkali metal includes KHSO4.

### Claim 3 (depends on 2)

The etchant of claim 2, further comprising a 0.02-10 wt % auxiliary oxidizer.

### Claim 4 (depends on 3)

The etchant of claim 3, wherein the auxiliary oxidizer is a compound of at least one selected from the group consisting of H3PO4, HNO3, CH3COOH, HClO4, H2O2, and oxone.

### Claim 5 (depends on 1)

The etchant of claim 1, wherein the hydrogen sulfate of an alkali metal includes KHSO4, further comprising a 0.02-10 wt % auxiliary oxidizer, further comprising a 0.01-5 wt % auxiliary inhibitor.

### Claim 6 (depends on 5)

The etchant of claim 5, wherein the auxiliary oxidizer is a compound of at least one selected from a group consisting of H3PO4, HNO3, CH3COOH, HClO4, H2O2, and oxone.

### Claim 7 (depends on 5)

The etchant of claim 5, wherein the auxiliary inhibitor is a compound of at least one selected from the group consisting of CH3COONH4, NH4SO3NH2, NH4C6H5O2, NH4COONH4, NH4Cl, NH4H2PO4, NH4OOCH, NH4HCO3, H4NO2CCH2C(OH)(CO2NH4)CH2CO2NH4, NH4PF6, HOC(CO2H)(CH2CO2NH4)2, NH4NO3, (NH4)2S2O8, H2NSO3NH4, and (NH4)2SO4.

### Claim 8 (depends on 1)

The etchant of claim 1, wherein the hydrogen sulphate of an alkali metal includes KHSO4, further comprising 0.01-5 wt % auxiliary inhibitor.

### Claim 9 (depends on 8)

The etchant of claim 8, wherein the auxiliary inhibitor is a compound of at least one selected from the group consisting of CH3COONH4, NH4SO3NH2, NH4C6H5O2, NH4COONH4, NH4Cl, NH4H2PO4, NH4OOCH, NH4HCO3, H4NO2CCH2C(OH)(CO2NH4)CH2CO2NH4, NH4PF6, HOC(CO2H)(CH2CO2NH4)2, NH4NO3, (NH4)2S2O8, H2NSO3NH4, and (NH4)2SO4.

### Claim 10 (depends on 1)

The etchant of claim 1, further comprising a 0.02-10 wt % auxiliary oxidizer.

### Claim 11 (depends on 10)

The etchant of claim 10, wherein the auxiliary oxidizer is a compound of at least one selected from the group consisting of H3PO4, HNO3, CH3COOH, HClO4, H2O2, and oxone.

### Claim 12 (depends on 1)

The etchant of claim 1, further comprising a 0.02-10 wt % auxiliary oxidizer, further comprising a 0.01-5 wt % auxiliary inhibitor.

### Claim 13 (depends on 12)

The etchant of claim 12, wherein the auxiliary oxidizer is a compound of at least one selected from the group consisting of H3PO4, HNO3, CH3COOH, HClO4, H2O2, and oxone.

### Claim 14 (depends on 12)

The etchant of claim 12, wherein the auxiliary inhibitor is a compound of at least one selected form the group consisting of CH3COONH4, NH4SO3NH2, NH4C6H5O2, NH4COONH4, NH4Cl, NH4H2PO4, NH4OOCH, NH4HCO3, H4NO2CCH2C(OH)(CO2NH4)CH2CO2NH4, NH4PF6, HOC(CO2H)(CH2CO2NH4)2, NH4NO3, (NH4)2S2O8, H2NSO3NH4, and (NH4)2SO4.

### Claim 15 (depends on 1)

The etchant of claim 1, further comprising a 0.01-5 wt % auxiliary inhibitor.

### Claim 16 (depends on 15)

The etchant of claim 15, wherein the auxiliary inhibitor is a compound of at least one selected from the group consisting of CH3COONH4, NH4SO3NH2, NH4C6H5O2, NH4COONH4, NH4Cl, NH4H2PO4, NH4OOCH, NH4HCO3, H4NO2CCH2C(OH)(CO2NH4)CH2CO2NH4, NH4PF6, HOC(CO2H)(CH2CO2NH4)2, NH4NO3, (NH4)2S2O8, H2NSO3NH4, and (NH4)2SO4.

### Claim 17 (depends on 1)

The etchant of claim 1, wherein the indium tin oxide (ITO) is amorphous indium tin oxide (ITO).

### Claim 18

An etchant for a transparent conductive oxide layer, comprising:
2-15 wt % sulfuric acid;
0.02-10 wt % hydrogen sulfate of alkali metal;
a 0.02-10 wt % auxiliary oxidizer;
a 0.01-5 wt % auxiliary inhibitor; and
deionized water as the remainder,
wherein the transparent conductive oxide layer is made of indium tin oxide (ITO) or indium zinc oxide (IZO).

### Claim 19 (depends on 18)

The etchant of claim 18, wherein hydrogen sulfate of alkali metal includes KHSO4.

### Claim 20 (depends on 18)

The etchant of claim 18, wherein the auxiliary oxidizer is a compound of at least one selected from the group consisting of H3PO4, HNO3, CH3COOH, HClO4, H2O2, and oxone.

### Claim 21 (depends on 18)

The etchant of claim 18, wherein the auxiliary inhibitor is a compound of at least one selected from the group consisting of CH3COONH4, NH4SO3NH2, NH4C6H5O2, NH4COONH4, NH4Cl, NH4H2PO4, NH4OOCH, NH4HCO3, H4NO2CCH2C(OH)(CO2NH4)CH2CO2NH4, NH4PF6, HOC(CO2H)(CH2CO2NH4)2, NH4NO3, (NH4)2S2O8, H2NSO3NH4, and (NH4)2SO4.

### Claim 22 (depends on 18)

The etchant of claim 18, wherein the indium tin oxide (ITO) is amorphous indium tin oxide (ITO).

### Claim 23 (depends on 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)

A method for fabricating a liquid crystal display (LCD), the method comprising:
providing an insulating substrate in which a transparent conductive oxide layer is formed; and
patterning the transparent conductive oxide layer by etching the transparent conductive oxide layer using the etchant of one of claims 1 to 14.

### Claim 24 (depends on 23)

The method of claim 23, wherein the etching is performed at 30-50° C.

### Claim 25 (depends on 23)

The method of claim 23, wherein the etching is performed for 20-100 seconds.

### Claim 26 (depends on 23)

The method of claim 23, wherein the transparent conductive oxide layer is made of indium tin oxide (ITO) or indium zinc oxide (IZO).

### Claim 27 (depends on 26)

The method of claim 26, wherein the indium tin oxide (ITO) is amorphous indium tin oxide (ITO).