Chemistry: electrical and wave energy – Apparatus – Coating – forming or etching by sputtering
Reexamination Certificate
1999-11-03
2002-07-30
McDonald, Rodney G. (Department: 1753)
Chemistry: electrical and wave energy
Apparatus
Coating, forming or etching by sputtering
C204S298090, C118S725000, C118S728000, C118S500000, C156S345420
Reexamination Certificate
active
06425994
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process chamber and more specifically, a process chamber in which plasma enhanced chemical vapor deposition, sputtering, and other similar processes are performed on a substrate such as glass.
2. Discussion of Related Art
A multitude of general processes such as chemical vapor deposition, sputtering, etching and other similar processes can be carried out in a process chamber, for example, for forming layers of a thin film transistor on a substrate.
In the present description, a thermal process such as annealing is used as an example of a process performed in the process chamber. In a thermal process, a substrate that is disposed on a stage has heat transferred to the substrate via a heating coil that transforms electric energy into thermal energy. The heating coil heats the substrate so as to maintain a temperature that can accelerate the reaction between the substrate and process gases flowing in the process chamber.
FIG. 1
is a cross-sectional view of a stage according to the related art.
FIG. 2
is a cross-sectional view of a process chamber including the stage shown in FIG.
1
.
The stage shown in
FIGS. 1 and 2
is a unitary, integral member including both a main base portion
100
and a substrate mounting portion
160
.
Referring to FIG.
1
and
FIG. 2
, a stage is installed at the lower portion of the process chamber. The stage includes the main base portion
100
, the substrate mounting portion
160
, a heating coil
104
, and a power supply
110
.
The substrate mounting portion
160
protrudes upward and is located at the top part of the base portion
100
. The base portion
100
also includes a built-in heating coil
104
. The power supply
110
connects to the heating coil
104
so that by supplying the heating coil
104
with electric current, the heating coil
104
can transform electric energy to thermal energy.
Thus, the base portion
100
and the substrate mounting portion
160
define a unitary stage according to the related art.
Note that recesses on either side of the related art substrate mounting portion
160
are provided to accommodate fixing members (not shown) such as a fixing jig referred to as a “shadow frame”to hold a substrate
140
on the substrate mounting portion
160
.
When a substrate
140
is to be processed in the chamber, the substrate
140
is placed on the substrate mounting portion
160
and securing the shadow frames to the recesses at ends of the substrate mounting portion
160
to hold the substrate
140
in place on the substrate mounting portion
160
during the thermal processing in the chamber.
The substrate mounting portion
160
is usually made of aluminum, but can also be made of ceramic or quartz. The substrate mounting portion
160
is usually made of aluminum because quartz and ceramic are much more expensive materials and damaged easily because they react with F radical of process gas.
Also, because ceramic is lower heat conductivity than aluminum, it takes long time to heat ceramic.
So, they are The substrate mounting portion
160
made of aluminum requires an insulating layer disposed between the substrate mounting portion and the substrate in order to protect the substrate and to prevent the aluminum material from conducting current from the aluminum to the substrate thereby causing damage to TFT layers (not shown) later formed on the substrate during processing in the chamber.
A bellows
130
is placed at the exterior lower surface of the process chamber
150
so that the base portion
100
and the process chamber
150
is sealed. A support
106
includes a shaft
108
that rises or falls so as to maintain a proper distance between the substrate
140
and a gas emitting gas diffuser
154
. Note that the gas diffuser
154
has a plurality of holes
156
so that gas from the gas supply
152
can be injected into the process chamber
150
. Further, an outlet
158
exists at the bottom of the process chamber
150
.
Process gas from the gas supply
152
is injected into the inner cavity of the process chamber
150
through the plurality of holes
156
defined in the gas diffuser
154
. Note that the process gas turns into a plasma due to the RF power. A semiconductor layer (not shown) is formed on the substrate
140
as a result of the reaction of the process gas, in the plasma state, with the substrate
140
. Note that to form the semiconductor layer, the substrate
140
has been mounted on the substrate mounting portion
160
and has been heated by the heating coil
104
to a temperature that is suitable for deposition of a film. Thereafter, the by-products from the thermal process are exhausted through the outlet
158
.
Next, a related art process for maintaining a desired substrate temperature that is required for the above-described thermal process will be explained below.
The substrate
140
is placed on the substrate mounting portion
160
by a transporting unit(not shown in the drawing) such as a robot arm or other similar devices. Also, the proper distance between the gas diffuser
154
and the substrate
140
in the process chamber
150
is accomplished by having the shaft
108
rise or fall as needed for accurate positioning. Next, when the power supply
110
is turned on, the heat generated from the heating coil
104
conducts to the substrate mounting portion
160
and the substrate
140
disposed thereon, thus setting the proper temperature for the thermal process.
However, in the related art, the thermal process exposes the substrate mounting portion
160
to heat and gases that damage and contaminate the substrate mounting portion
160
, and especially the surface protecting layer that is between the substrate mounting portion
160
and the substrate
140
, if the substrate mounting portion is made of aluminum. If the substrate mounting portion
160
is made of quartz or ceramic, the substrate mounting portion
160
is also damaged by the heat and gases because quartz and ceramic materials react with F radical of process gas and ceramic is low heat conductivity.
Because the base portion
100
and the substrate mounting portion
160
define a major portion of a unitary stage, the whole stage must be replaced even though only the surface protecting layer or the substrate mounting portion
160
is damaged. The stage must also be replaced periodically with a new stage by opening the process chamber and then removing the stage from the chamber.
Further, the new stage needs to be set up again, thus consuming a large amount of process time and incurring additional costs.
SUMMARY OF THE INVENTION
To solve the problems described above, preferred embodiments of the present invention provide a process chamber that allows easy replacement of the substrate mounting member without having to replace the entire stage. Also, the present invention eliminates waste of process time and is constructed to allow very easy and quick replacement of a substrate mounting member.
One preferred embodiment of the present invention provides a process chamber including a main base, a substrate mounting member mounted on the main base and having a substrate mounted thereon, wherein the substrate mounting member is arranged to allow removal of the substrate mounting member.
Another preferred embodiment of the present invention provides a process chamber including a main base including a recessed portion and a protrusion at each of opposite ends thereof, a substrate mounting member mounted on the main base and arranged such that a portion of the substrate mounting member is disposed within the recessed portion of the main base and between the protrusions at the opposite ends of the main base.
Another preferred embodiment of the present invention provides a process chamber which preferably includes a main base, and a substrate mounting member which is independent of the main base and removably mounted on the main base, and arranged to support a substrate during processing.
In preferred embodiments of the present invention, the substrate mounting member
Choi Chang-Hoon
Lee In-Won
Park Man-Jong
Birch & Stewart Kolasch & Birch, LLP
Cantelmo Gregg
LG.Philips LCD Co. , Ltd.
McDonald Rodney G.
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