Etchant for etching metal wiring layers and method for forming thin film transistor by using the same
The present invention discloses an etchant for etching at least two different metal layers, the etchant comprising hydrogen peroxide (H 2 O 2 ) and one of carboxylic acid, carboxylate salt, and acetyl group (CH 3 CO—). The present invention also discloses a method of fabricating a metal wiring on a substrate, the method comprising forming a first metal layer on a substrate, forming a second metal layer on the first metal layer, and simultaneously etching the first metal layer and the second metal layer with an etchant comprising hydrogen peroxide (H 2 O 2 ) and one of carboxylic acid, carboxylate salt, and acetyl group (CH 3 CO—).
1. A method of fabricating a thin film transistor, comprising:
forming first metal layers including at least two different metal layers on a substrate;
forming a gate electrode and a gate line by etching with an etchant comprising hydrogen peroxide (H 2 O 2 ) and one of carboxylic acid, carboxylate salt, and acetyl group (CH 3 CO—);
forming a gate insulation layer on the substrate to cover the gate electrode and the gate line;
sequentially forming an active layer and an ohmic contact layer on the gate insulation layer;
forming second metal layers including the at least two different metal layers on the substrate;
etching the second metal layers to form a source electrode and a drain electrode;
forming a protective layer to cover the source electrode and the drain electrode on the gate insulation layer with a contact hole for exposing the drain electrode; and
forming a pixel electrode connected to the drain electrode through the contact hole.
2. The method according to claim 1 , wherein a concentration of one of carboxylic acid, carboxylate salt, and acetyl group (CH 3 CO—) is substantially in the range of 0.5 wt % to 3 wt %.
3. The method according to claim 1 , wherein a concentration of hydrogen peroxide (H 2 O 2 ) is substantially 0.1 mol or more.
4. The method according to claim 1 , wherein a concentration of one of carboxylic acid, carboxylate salt, and acetyl group (CH 3 CO—) is substantially 0.5 wt % or more and a concentration of hydrogen peroxide (H 2 O 2 ) is substantially 0.1 mol or more.
5. The method according to claim 1 , wherein at least one of the first metal layers and the second metal layers includes a double layered structure having copper (Cu) layer.
6. The method according to claim 1 , wherein the pixel electrode is formed on the protective layer.
7. The method according to claim 1 , wherein the pixel electrode is formed of one of ITO, IZO, and ITZO.
8. The method according to claim 1 , wherein the etching the second metal layers uses an etchant comprising hydrogen peroxide (H 2 O 2 ) and one of carboxylic acid, carboxylate salt, and acetyl group (CH 3 CO—).
9. The method according to claim 1 , wherein the carboxylic acid includes —COOH.
10. The method according to claim 1 , wherein the first metal layers or the second metal layers include at least copper/titanium (Cu/Ti).
11. The method according to claim 1 , wherein the first metal layers or the second metal layers include at least titanium/copper/titanium (Ti/Cu/Ti).
12. The method according to claim 1 , wherein the first metal layers or the second metal layers include an upper layer and a lower layer, and the upper layer is thicker than the lower layer.
13. The method according to claim 1 , wherein the etchant further comprises fluorine (F).
14. The method according to claim 13 , wherein the fluorine (F) includes one of hydrogenfluoric acid (HF), ammonium fluoride (NH 4 F), potassium fluoride (KF), sodium fluoride (NaF), and potassium bifluoride (KHF 2 ).
15. The method according to claim 1 , wherein at least one of the first metal layers and the second metal layers includes a triple layered structure having copper (Cu) layer.
16. The method according to claim 15 , wherein the copper (Cu) layer is interposed between a bottom layer and a top layer.
17. The method according to claim 1 , wherein the protective layer includes one of an inorganic insulation material and an organic insulation material.
18. The method according to claim 17 , wherein the organic insulation material includes one of an acrylic organic compound, benzocyclobytene (BCB), and perfluorocyclobutane (PFCB).