KR20020078583A - Etchant for manufacturing source and drain electrode in tft-lcd - Google Patents

Abstract

PURPOSE: An etchant for manufacturing source and drain electrode in TFT (thin film transistor)-LCD is provided, which is possible to carry out taper etching with no shoulder. CONSTITUTION: In an etchant for dry etching Mo film or Mo·W alloy film used as source and drain electrode in TFT (thin film transistor)-LCD, the etchant comprises phosphoric acid 30 to 80 wt.%, nitric acid 1.0 to 25 wt.%, acetic acid 2.0 to 20 wt.%, oxidation controller (HClO4 or HIO4) 0.1 to 10 wt.% and a balance of water.

Description

Etching composition for source and drain electrodes of liquid crystal display device for thin film transistors {Etchant for manufacturing source and drain electrode in TFT-LCD}

The present invention is wet etching after coating and exposing a photoresist of a Mo film or a Mo-W alloy film, which is a metal wiring material for a source and a drain electrode, constituting a TFT (Thin Film Transistor) of a liquid crystal display device. It relates to an etching solution composition to obtain a desired pattern by.

Conventionally, a pattern was prepared by using a regular Al monolayer etching solution consisting of phosphoric acid + nitric acid + acetic acid + water or by dry etching.

The etching method of the Mo film or the Mo-W alloy film using the regular Al single layer etching solution does not form a desired perfect pattern, and the surface is not smooth and protrudes as shown in FIG. The cause of the Schulder phenomenon is interpreted as a phenomenon due to an uneven interface reaction in an aqueous solution.

When dry etching is performed in an expensive vacuum equipment, an ashing process using oxygen plasma is performed to remove some hardened photoresist on the surface during the etching process, and then to remove residual photoresist. Since the process steps are complicated, such as performing a strip process and a separate cleaning process, manufacturing costs increase.

SUMMARY OF THE INVENTION In view of the above, the present invention relates to a source and drain electrode of a TFT of a thin film transistor liquid crystal display using an etchant added with an additional oxidation modifier to a conventional etchant comprising a composition of phosphoric acid + nitric acid + acetic acid + water. It is to allow the wet etching of the Mo film or the Mo · W alloy film in a uniform pattern.

1 is a photograph showing an electron microscope view of a cross section of an Mo film or an Mo · W alloy film as a source and drain electrode material after a wet etching process using an etchant of the present invention.

FIG. 2 is a photograph showing an electron microscope view of a cross section of a Mo film or an Mo · W alloy film that is a source and drain electrode material after wet etching with a conventional etching solution. FIG.

In the present invention, in order to obtain a Mo film or a Mo · W alloy film having a uniform pattern in the source and drain electrode forming process of the thin film transistor liquid crystal display device, the conventional etching solution used in the conventional etching process of phosphoric acid + nitric acid + acetic acid + water An additional oxidation regulator is added to the composition to perform wet etching of the Mo film or the Mo · W alloy film.

When wet etching was performed by adding an oxidizing agent to the existing etching solution, taper etching with a uniform inclination angle of the Mo film or the Mo · W alloy film was obtained.

This taper etching is possible by adding an additional redox regulator to the existing etchant to control the etch rate at the interface by the redox reaction to suppress the non-uniform interfacial reaction.

The oxidation regulator which can be added to the conventional etching solution may be H ₂ O ₂ , K ₂ Cr ₂ O ₇ , HClO ₄ , HIO ₄ and the like, but the oxidation regulator of HClO ₄ or HIO ₄ is preferable.

The composition ratio of the etchant of the present invention is composed of phosphoric acid (30-80wt%) + nitric acid (1.0-25wt%) + acetic acid (2.0 -20wt%) + oxidation regulator (0.1-10wt%) and the oxidation regulator is HClO ₄ or HIO ₄ is preferred, and the oxidizing agent composition ratio is suitably 1-6 wt%, and the remainder of the etching liquid composition is composed of water (H ₂ O).

Phosphoric acid (30-80wt%) + nitric acid (1.0) which can be etched in a desired pattern in the process of forming a Mo film or a Mo-W alloy film used as a source and drain electrode constituting the TFT of the thin film transistor liquid crystal display according to the present invention. -25wt%) + Acetic acid (2.0-20wt%) + Oxidation modifier (0.1-10wt%) + Wet etching solution of Mo film or Mo · W alloy film with water composition. Tapered etching and uniform etching are possible. Improvements can be made.

Claims (2)

In an etchant that wet-etches a Mo film or a Mo-W alloy film used as a source and a drain electrode constituting a TFT of a thin film transistor liquid crystal display device, An etchant composition for source and drain electrodes of a thin film transistor liquid crystal display device comprising phosphoric acid (30-80 wt%) + nitric acid (1.0-25 wt%) + acetic acid (2.0-20 wt%) + oxidation regulator (0.1-10 wt%) + water. The etchant composition of claim 1, wherein the oxidation regulator (0.1-10 wt%) is HClO ₄ or HIO ₄ .