JPH05343365A - Dry etching method - Google Patents

Abstract

PURPOSE:To rapidly etch an ITO by using a plasma which does not generate reaction product for disturbing etching reaction by using gas containing hydrogen bromide as etching gas. CONSTITUTION:An ITO film (In-Sn oxide) 11 is formed on a base film 12, an article 8 to be etched and formed with a resist film 10 on this electrode forming part is disposed on a cathode 4, and hydrogen bromide is introduced. A high frequency power source 7 is connected to the cathode 4 through an impedance matching circuit 6, a high frequency discharging is generated between the cathode 4 and an anode 3, a plasma is generated to etch the film 11. Thus, reaction product for disturbing etching reaction is not generated by using the gas containing the hydrogen bromide as the etching gas, and hence the ITO can be rapidly etched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching method for etching ITO (In-Sn oxide) used for transparent electrodes by using gas plasma.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays are thin, lightweight,
It has attracted attention as a low power consumption display, and IT
O is used as a transparent electrode of such a liquid crystal display.

In general, the forming method is to perform fine processing by forming an ITO film, covering a portion to be an electrode with a resist film by a photolithography technique, and then etching. As this etching method, for example, the method disclosed in Japanese Patent Laid-Open No. 52-119246 is known. The etching method is a method of forming an electrode pattern by selectively etching ITO with alcohol or carboxylic acid gas plasma. In this method, it is considered that the oxide of In and Sn is reduced by hydrogen activated by plasma, and In and Sn react with the alkyl group gas to be gasified.

[0004]

However, in the above method, the alcohol or carboxylic acid which has not reacted with In or Sn produces an organic compound having a high boiling point, which hinders the progress of the reaction, resulting in a small etching rate. Had a problem.

In view of the above conventional problems, it is an object of the present invention to provide a dry etching method for etching ITO at a high speed by using plasma that does not generate a reaction product that interferes with the etching reaction.

[0006]

The dry etching method of the present invention is characterized in that a gas containing hydrogen bromide is used as an etching gas.

A gas containing boron trichloride in addition to hydrogen bromide is used as an etching gas depending on the case.

[0008]

In the present invention, by using hydrogen bromide gas, the etching reaction is as follows. First, the active hydrogen generated in the plasma reduces the ITO to cause In and Sn.
The In and Sn react with bromine in the active state to form bromide, which is gasified and etching proceeds. At this time, the plasma of alcohol or carboxylic acid produces a reaction product that significantly inhibits the etching reaction, but since such a reaction product cannot be formed with hydrogen bromide gas, high-speed etching of ITO becomes possible.

When the reduction reaction by hydrogen in the active state generated in hydrogen bromide gas plasma is not sufficient, a residue may be generated, but the addition of boron trichloride enhances the reducing property. The etching can be advanced and the generation of residue can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dry etching method according to a first embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, a reaction gas is introduced into a metal reaction chamber 1 through a gas controller 5, and an exhaust system 2 is provided.
Is controlled to an appropriate pressure. An anode (anode) 3 is provided in the upper part of the reaction chamber 1, and a cathode (cathode) 4 is provided in the lower part of the reaction chamber 1, and the etching target 8 is arranged on the cathode 4. A high frequency power supply 7 is connected to the cathode 4 via an impedance matching circuit 6, and a high frequency discharge is generated between the cathode 4 and the anode 3 to generate plasma. Reference numeral 9 denotes a push-up mechanism that pushes up the object to be etched 8 from the upper surface of the cathode 4 after processing.

In this dry etching apparatus, an object to be etched 8 (see FIGS. 2 to 4) in which an ITO film 11 is formed on a base film 12 and a resist film 10 is formed on an electrode forming portion thereof is formed on a cathode 4. Place and introduce hydrogen bromide,
A high-frequency power of 400 W was applied to generate plasma to etch the ITO film 11. The etching rate was about 500 Å / min.

On the other hand, when methyl alcohol was used as the etching gas, the etching rate was about 200 angstroms / minute, so that the use of the present invention improved the etching rate more than twice as much as the conventional method. .

In this embodiment, the ITO film 11 is also used.
Since the ITO film 11 has a sawtooth shape as shown in FIG. 2 when the etching target 8 is etched halfway, an etching residue may remain as shown in FIG. 3 without overetching. However, if the etching rate of the ITO film 11 is sufficiently higher than the etching rate of the base film 12, overetching makes it possible to obtain a completely etched shape as shown in FIG.

Next, a second embodiment of the present invention will be described with reference to FIG.
Will be described with reference to.

In the same device as in the first embodiment, ITO was similarly used.
The etching object 8 having the pattern of the resist film 10 on the film 11 is arranged on the cathode 4, hydrogen bromide and boron trichloride are introduced at a volume ratio of 1: 1 and a high frequency power of 400 W is applied. The ITO film 11 was etched by generating plasma. At this time, the etching rate was about 350 angstroms / minute, which was smaller than that of the first embodiment, but the shape of the etching object 8 obtained by etching the ITO film 11 halfway was smooth as shown in FIG. Could be etched into. Therefore, in this embodiment, even if the difference between the etching rate of the ITO film 11 and the etching rate of the base film 12 is small, it is possible to obtain an etching shape without a residue as shown in FIG.

In the above embodiment, the purpose of the etching is to leave no residue. However, the present invention may be used for etching to generate a residue or to process the ITO film 11 into a sawtooth shape.

A gas other than hydrogen bromide or boron trichloride may be added as a carrier gas in order to change the difference in etching rate from the underlying film 12 or to control the shape.

[0019]

According to the present invention, by using a gas containing hydrogen bromide as an etching gas as described above,
It does not generate reaction products that interfere with the etching reaction, and thus the ITO can be etched at a high speed.

Further, by adding boron trichloride, the reducing property becomes stronger and the generation of residue can be prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a dry etching apparatus used in an embodiment of the present invention.

FIG. 2 is a schematic view showing a cross-sectional shape of an object to be etched when the ITO film is partially etched in the first embodiment of the present invention.

FIG. 3 is a schematic view showing a cross-sectional shape of an object to be etched when the ITO film is etched without overetching in the example.

FIG. 4 is a schematic view showing a cross-sectional shape of an object to be etched when the ITO film is over-etched in the example.

FIG. 5 is a schematic diagram showing a cross-sectional shape of an object to be etched when the ITO film is partially etched in the second embodiment of the present invention.

[Explanation of symbols]

 1 Reaction Chamber 5 Gas Controller 7 High Frequency Power Supply 8 Etching Object

Claims (3)

[Claims] 1. An ITO-containing object to be etched is placed in a reaction chamber, plasma is generated by introducing an etching gas into the reaction chamber and applying high-frequency power to etch the ITO to be etched in the reaction chamber. In the dry etching method described above, a gas containing hydrogen bromide is used as an etching gas. 2. The dry etching method according to claim 1, wherein a gas containing boron trichloride other than hydrogen bromide is used as an etching gas. 3. The dry etching method according to claim 2, wherein the volume ratio of hydrogen bromide and boron trichloride contained in the etching gas is approximately 1: 1.