Electric heating – Metal heating – By arc
Reexamination Certificate
2001-12-28
2004-06-29
Van, Quang T. (Department: 3742)
Electric heating
Metal heating
By arc
C219S121520, C219S121510, C219S121430, C156S345470
Reexamination Certificate
active
06756559
ABSTRACT:
This application claims the benefit of Korean Patent Application No. 2000-83768, filed on Dec. 28, 2000 in Korea, which is hereby incorporated by reference as if fully set forth herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma processing apparatus, and more particularly to a plasma etching apparatus which dry-etches thin films or layers formed on a substrate for a liquid crystal display.
2. Discussion of Related Art
Plasma is an electrically neutral, highly organized gas composed of ions, electrons and neutral particles. The plasma is a phase of matter distinct from solids, liquids, and normal gases. Because plasmas are conductive and respond to electric and magnetic fields and can be efficient sources of radiation, they are usable in numerous applications where such control is needed or when special sources of energy or radiation are required. In recent years, such plasmas are introduced in the areas of plasma technology, such as thin film deposition, display systems (e.g., Plasma Display Panel (PDP)), bulk materials work, plasma-based lighting systems, environmental and health applications and materials synthesis. Among the various areas of plasma technology, plasmas are especially adopted in the field of manufacturing semiconductor devices and liquid crystal display devices, which need large-scale integrated circuits.
A plasma etching apparatus generally etches polymer and metal layers using plasmas generated by the glow discharge at a low temperature, thereby forming the large-scale integrated devices. The plasma etching apparatus widely includes a reaction chamber, a gas feeding member and a voltage supply. The reaction chamber is a sealed container containing processing gases and the gas feeding member introduces reaction gases into the reaction chamber. The voltage supply is connected to electrodes inside the reaction chamber and applies a radio frequency (RF) power to generate plasmas in the reaction chamber. The processing gases from the gas feeding member are converted into the plasmas in the reaction chamber by the electrodes.
FIG. 1
is a schematic sectional view of a conventional plasma etching apparatus. As shown in
FIG. 1
, the conventional plasma etching apparatus
1
includes a reaction chamber
1
a
, a radio frequency (RF) power supply
17
and gas-exhaust members
22
and
24
. The reaction chamber
1
widely includes a gas inlet
6
through which processing gases are introduced, a plasma diffusing area
2
where the processing gases diffuse, and a reaction area
4
where plasmas are generated from the processing gases and etch an object
14
. A diffusion plate
8
having a plurality of holes or slits therein is located inside the plasma diffusing area
2
. The diffusion plate
8
diffuses the processing gases introduced from the gas inlet
6
, whereby the processing gases are easily spread into the reaction area
4
. An upper electrode
10
formed of a metallic material is disposed between the plasma diffusing area
2
and the reaction area
4
, and acts as a first electrode to generate an electric field when creating the plasmas. An insulator
12
is adjacent to the upper electrode
10
. The upper electrode
10
and the insulator
12
generally have a great number of holes (about ten thousands of holes) therein in order to freely ventilate the processing gases.
Still referring to
FIG. 1
, an object
14
, such as a glass substrate or a semiconductor wafer, is located in the reaction area
4
. A lower electrode
18
receiving the RF power from the RF power supply
17
is arranged at the bottom of the reaction area
4
. The lower electrode
18
serves as a second electrode when forming the plasmas using the processing gases. In the reaction area
4
, the object
14
(e.g., the substrate or semiconductor wafer) is etched by the plasmas generated by the upper and lower electrodes
10
and
18
.
The lower electrode
18
is preferably made of a metallic material coated with aluminum, and the object
14
is disposed on the aluminum-coated lower electrode
18
. A buffer plate
20
having a plurality of vent holes surrounds the lower electrode
18
at the bottom of the reaction area
4
. A shielding member
16
made of a ceramic material is disposed between the lower electrode
18
and the buffer plate
20
, and surrounds the lower electrode
18
in order to prevent the lower electrode
18
from being exposed. Accordingly, the buffer plate
20
, shielding member
16
and lower electrode
18
are located on the same plane at the bottom of the reaction area
4
. Further, the object
14
is mounted on an exposed portion of the lower electrode
18
. At the bottom of the reaction chamber
1
a
, the gas-exhausting members
22
and
24
, such as vacuum pumps, are disposed in order to remove the gaseous byproducts from the reaction area
4
.
The plasma etch processes performed in the above-mentioned plasma etching apparatus
1
will be explained hereinafter. The object
4
having the polymer or metal layer for plasma etching is loaded on the exposed portion of the lower electrode
18
. At this time, the object
4
has substantially the same size as the exposed portion of the lower electrode
18
. Thereafter, the processing gases flow into the plasma diffusing area
2
through the gas inlet
6
, and then the processing gases are diffused by the diffusion plate
8
. The diffused processing gases are then spread into the reaction area
4
through the plurality of holes of the upper electrode
10
and insulator
12
.
Thereafter, the RF power supply
17
applies the RF power to the lower electrode
18
, such that an electric field is induced between the upper electrode
10
and the lower electrode
18
. Therefore, the processing gases in the reaction area
4
are ionized to be the plasmas. The plasmas (e.g., the anions and cations) move toward the lower electrode with a high kinetic energy. The plasmas generated in the reaction area
4
allow for the ability to provide an anisotropic etch which is believed to depend on the bombardment with energetic ions on the surface of the object
14
. When etching the object
14
, the byproducts from the plasma etching are sucked through a plurality of holes through the buffer plate
20
by the gas-exhausting members
22
and
24
, which are below the reaction chamber
1
a
. Accordingly, the layers on the object
14
are patterned by the above-mentioned plasma etching processes.
FIG. 2
is a top plan view of the buffer plate
20
surrounding the shielding member
16
and lower electrode
18
. As shown in
FIG. 2
, the buffer plate
20
includes a plurality of holes
21
therein though which the gaseous byproducts and the residual plasma etchant are removed. Further in
FIG. 2
, the gas-exhausting members
22
and
24
(e.g., the vacuum pumps) sucking the gaseous byproducts and the residual plasma etchant are located below the reaction chamber
1
a
of
FIG. 1
in areas corresponding to areas “A” of FIG.
2
. When the gas-exhausting members
22
and
24
are operated, the gaseous byproducts and the residual plasma etchant are sucked by these gas-exhausting members
22
and
24
through the plurality of vent holes
21
. However, since the gas-exhausting members
22
and
24
are located in the areas “A”, the gaseous byproducts and the residual plasma etchant converge in these areas “A”.
In other words, when exhausting the gaseous byproducts and the residual etchant through the plurality of vent holes
21
of the buffer plate
20
, suction power is relatively larger in the areas “A” than the other area of the buffer plate
20
because the gas-exhausting members
22
and
24
are arranged under the areas “A”. Therefore, the density of the byproducts and etchant increases in the areas “A”, and then a convergence of the byproducts and etchant occurs in the areas “A”. Thus, the convergence of the gaseous byproducts and residual plasma etchant brings about the irregular etch of the object
14
(in
FIG. 1
) and additionally causes arcing in areas “B” of the lower electrode
18
.
The arcing ph
LG. Philips LCD Co. Ltd.
McKenna Long & Aldridge LLP
Van Quang T.
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