Etchant for etching double-layered copper structure and method of forming array substrate having double-layered copper structures

Abstract

An etchant for forming double-layered signal lines and electrodes of a liquid crystal display device includes hydrogen peroxide (H 2 O 2 ), a phosphate, F-ions, an organic acid having a carboxyl group (—COOH), a copper (Cu) inhibitor, and a hydrogen peroxide (H 2 O 2 ) stabilizer, wherein each of the double-layered signal lines and electrodes of the liquid crystal display device includes a first layer of one of aluminum (Al), aluminum alloy (Al-alloy), titanium (Ti), titanium alloy (Ti-alloy), tantalum (Ta), and a tantalum alloy (Ta-alloy) and a second layer of copper (Cu).

What is claimed is:  
     
         1 . An etchant for forming double-layered signal lines and electrodes of a liquid crystal display device, comprising: 
 hydrogen peroxide (H 2 O 2 );    a phosphate;    F-ions;    an organic acid having a carboxyl group (—COOH);    a copper (Cu) inhibitor; and    a hydrogen peroxide (H 2 O 2 ) stabilizer,    wherein each of the double-layered signal lines and electrodes of the liquid crystal display device includes a first layer of one of aluminum (Al), aluminum alloy (Al-alloy), titanium (Ti), titanium alloy (Ti-alloy), tantalum (Ta), and a tantalum alloy (Ta-alloy) and a second layer of copper (Cu).    
     
     
         2 . The etchant according to  claim 1 , wherein a concentration of hydrogen peroxide (H 2 O 2 ) is within a range from about 4% to about 40%, a concentration of the phosphoric acid is within a range from about 0.5% to about 10%, a concentration of the F-ions is within a range from about 0.01% to about 5%, a concentration of the organic acid is within a range from about 0.5% to about 10%, a concentration of the Cu etch inhibitor is within a range from about 0.2% to about 1.5%, and a concentration of the H 2 O 2  stabilizer is about 1%.  
     
     
         3 . The etchant according to  claim 1 , wherein the phosphate has a chemical formula of A X H Y PO 4 , wherein “A” is one of an alkali metal and an alkaline earth metal, “X” has a value within a range of about 1 to about 2, and “Y” has a value within a range of about 0 to about 2.  
     
     
         4 . The etchant according to  claim 3 , wherein the alkali metal is one of potassium (K) and sodium (Na), and the alkaline earth metal is one of calcium (Ca) and barium (Ba).  
     
     
         5 . The etchant according to  claim 3 , wherein the phosphate includes one of ammonium (NH 4 ) and ammonium derivatives.  
     
     
         6 . The etchant according to  claim 1 , wherein the organic acid is one of acetic acid (CH 3 COOH), formic acid (HCOOH), oxalic acid ((COOH) 2 ), citric acid (C 6 H 8 O 7 ), and glycolic acid (HOCH 2 COOH),  
     
     
         7 . The etchant according to  claim 1 , wherein the Cu etch inhibitor is an azole compound selected from a group consisting of methylimidazole (C 4 H 6 N 2 ) and pyrazole (NHNH 2 ).  
     
     
         8 . The etchant according to  claim 1 , wherein the Cu etch inhibitor is a triazole compound selected from a group consisting of tolytriazole (CH 3 N 3 ) and benzotriazole (C 6 H 5 N 3 ).  
     
     
         9 . The etchant according to  claim 1 , further comprising an additive having about a 1% concentration, wherein the additives are salicylic acid derivatives.  
     
     
         10 . The etchant according to  claim 1 , wherein the H 2 O 2  stabilizer is acetate selected from a group consisting of ammonium acetate (CH 3 COONH 4 ), potassium acetate (CH 3 COOK), and sodium acetate (CH 3 COONa).  
     
     
         11 . The etchant according to  claim 1 , wherein the F-ion is a fluoride selected from a group consisting of hydrofluoric acid (HF), ammonium fluoride (NH 4 F), potassium fluoride (KF), sodium fluoride (NaF), and ammonium hydrogen fluoride (NH 4 HF).  
     
     
         12 . A method of forming an array substrate of a liquid crystal display device, comprising: 
 forming a first metallic layer on a substrate;    forming a first copper (Cu) layer on the first metallic layer;    patterning the first metallic layer and the first Cu layer simultaneously using a first etchant to form a gate line and a gate electrode, the first etchant includes hydrogen peroxide (H 2 O 2 ), a phosphate, F-ions, an organic acid having a carboxyl group (—COOH), a copper (Cu) inhibitor, and a hydrogen peroxide (H 2 O 2 ) stabilizer;    forming a gate insulating layer over an entire surface of the substrate to cover the gate line and the gate electrode;    forming an active layer and an ohmic contact layer on the gate insulating layer and over the gate electrode;    forming a second metallic layer and a second copper (Cu) layer over the gate insulating layer to cover the active layer and the ohmic contact layer;    patterning the second metallic layer and the second Cu layer simultaneously using a second etchant to form a source electrode, a drain electrode, and a data line, the second etchant includes hydrogen peroxide (H 2 O 2 ), a phosphate, F-ions, an organic acid having a carboxyl group (—COOH), a copper (Cu) inhibitor, and a hydrogen peroxide (H 2 O 2 ) stabilizer;    forming a passivation layer over the gate insulating layer to cover the source and drain electrodes and the data line, the passivation layer having a drain contact hole exposing a portion of the data line; and    forming a pixel electrode on the passivation layer, the pixel electrode contacting the drain electrode through the drain contact hole.    
     
     
         13 . The method according to  claim 12 , wherein the gate insulating layer is an inorganic material selected from a group consisting of silicon nitride and silicon oxide, and the pixel electrode is formed of a transparent conductive material selected from a group consisting of indium tin oxide and indium zinc oxide.  
     
     
         14 . The method according to  claim 12 , wherein the first metallic layer is one of aluminum (Al) and an aluminum alloy (Al-alloy).  
     
     
         15 . The method according to  claim 12 , wherein the second metallic layer is one of titanium (Ti), tantalum (Ta), titanium alloy (Ti-alloy), and a tantalum alloy (Ta-alloy).  
     
     
         16 . The method according to  claim 12 , wherein a concentration of the hydrogen peroxide (H 2 O 2 ) is within a range from about 4% to about 40%, a concentration of the phosphoric acid is within a range from about 0.5% to about 10%, a concentration of the F-ions is within a range from about 0.01% to about 5%, a concentration of the organic acid is within a range from about 0.5% to about 10%, a concentration of the Cu etch inhibitor is within a range from about 0.2% to about 1.5%, and a concentration of the H 2 O 2  stabilizer is about 1%.  
     
     
         17 . The method according to  claim 12 , wherein the phosphate has a chemical formula of A X H Y PO 4 , wherein “A” is one of an alkali metal and an alkaline earth metal, “X” has a value within a range of about 1 to about 2, and “Y” has a value within a range of about 0 to about 2.  
     
     
         18 . The method according to  claim 17 , wherein the alkali metal is one of potassium (K) and sodium (Na), and the alkaline earth metal is one of calcium (Ca) and barium (Ba).  
     
     
         19 . The method according to  claim 17 , wherein the phosphate includes one of ammonium (NH 4 ) and ammonium derivatives.  
     
     
         20 . The method according to  claim 12 , wherein the organic acid is one of acetic acid (CH 3 COOH), formic acid (HCOOH), oxalic acid ((COOH) 2 ), citric acid (C 6 H 8 O 7 ), and glycolic acid (HOCH 2 COOH),  
     
     
         21 . The method according to  claim 12 , wherein the Cu etch inhibitor is an azole compound selected from a group consisting of methylimidazole (C 4 H 6 N 2 ) and pyrazole (NHNH 2 ).  
     
     
         22 . The method according to  claim 12 , wherein the Cu etch inhibitor is a triazole compound selected from a group consisting of tolytriazole (CH 3 N 3 ) and benzotriazole (C 6 H 5 N 3 ).  
     
     
         23 . The method according to  claim 12 , further comprising an additive having about a 1% concentration, wherein the additives are salicylic acid derivatives.  
     
     
         24 . The method according to  claim 12 , wherein the H 2 O 2  stabilizer is acetate selected from a group consisting of ammonium acetate (CH 3 COONH 4 ), potassium acetate (CH 3 COOK), and sodium acetate (CH 3 COONa).  
     
     
         25 . The method according to  claim 12 , wherein the F-ion is a fluoride selected from a group consisting of hydrofluoric acid (HF), ammonium fluoride (NH 4 F), potassium fluoride (KF), sodium fluoride (NaF), and ammonium hydrogen fluoride (NH 4 HF).