Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
1999-09-24
2001-03-20
Mills, Gregory (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C118S728000, C118S7230ER, C156S345420
Reexamination Certificate
active
06202590
ABSTRACT:
This application relies for priority upon Korean Patent Application Nos. 98-39952 and 99-27461, filed on Sep. 25, 1998, and Jul. 8, 1999, respectively, the contents of which are herein incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for fabricating semiconductor devices, and more particularly, to an apparatus for fabricating semiconductor devices using plasma.
2. Description of the Related Art
As the integration of semiconductor devices increases, the demand for a deposition technique to form a material film having a uniform thickness, or an etching technique showing a uniform etch rate also increases. Accordingly, a plasma apparatus for depositing a material film or etching the material film by appropriately controlling the type of ions and ion energies is being widely used for the manufacture of highly-integrated semiconductor devices. To be more specific, the plasma apparatus can be applied to dry etching, chemical vapor deposition (CVD) or sputtering techniques.
Meanwhile, a radio frequency generator is widely used as an energy source for generating the plasma used in these techniques.
FIG. 1A
is a schematic of a conventional plasma apparatus, and
FIG. 1B
is a plan view of the chuck and the gas injection ring shown in FIG.
1
A.
Referring to
FIG. 1A
, a chuck
5
is installed on the bottom of a chamber
10
, which has an opening at the top, and a chuck support
15
made of an insulating material is interposed between the chuck
5
and the bottom of the chamber
10
. A wafer on which a semiconductor device is to be formed, is loaded on the chuck
5
. A gas injection ring
20
is installed around the sidewall of the chuck
5
, and is fixed by a fixing means
25
such as a bolt in contact with the bottom of the chamber
10
. The gas injection ring
20
is preferably attached in such a way that it is electrically connected to the chamber
10
, which has a ground potential. The chuck
5
and the gas injection ring
20
are spaced apart from each other by a predetermined interval, for example, at an interval of about 1 to 5 mm. Thus, a gap exists between the chuck
5
and the gas injection ring
20
, such that the gas injection ring
20
and the chuck
5
form a chuck capacitor.
The sidewall of the chamber
10
or a predetermined area of the bottom of the chamber
10
is branched and connected to a vacuum pump
30
. The opening of the chamber
10
is covered by a cover
35
, which is formed of a dielectric material. An electrode
40
connected to a first plasma power source
45
a
for generating radio frequency power, is installed over the cover
35
. Thus, when the first plasma power source
45
a
is turned on, plasma is generated within the chamber
10
.
A first radio frequency matching circuit
50
a
for maximizing the transmission efficiency of radio frequency power generated from the first plasma power source
45
a
is interposed between the first plasma power source
45
a
and the electrode
40
. The chuck
5
is connected to a second plasma power source
45
b
, which is used to induce plasma generated within the chamber
10
by the first plasma power source
45
a
over the chuck
5
.
A gas injection passage for supplying process gas into the chamber
10
is installed within the gas injection ring
20
. The gas injection passage is connected to a tank
55
which contains a gas source, via a gas inlet. A second radio frequency matching circuit
50
b
having the same function as that of
50
a
is interposed between the second plasma power source
45
b
and the chuck
5
. A valve
60
for controlling the flow of gas is installed at a predetermined position on the gas inlet between the tank
55
and the gas injection ring
20
. The valve
60
and the pump
30
are controlled by a valve control signal &PHgr;
v
and a pump control signal &PHgr;
p
, respectively, which are generated from a system controller
65
that controls the operation of the plasma apparatus. The system controller
65
receives signals from the first and second plasma power sources
45
a
and
45
b
and detects an on/off state of each of the first and second plasma power sources
45
a
and
45
b.
As described above, the total chuck capacitance between the chuck
5
and a ground terminal is directly affected by the change in chuck capacitance between the chuck
5
and the gas injection ring
20
. Thus, when the chuck capacitance is changed, the total chuck capacitance is also changed. The total chuck capacitance in turn directly affects a plasma process. This means that when the total chuck capacitance is changed, the sheath potential between the chuck
5
and the plasma induced over the chuck
5
by the second plasma power source
45
b
is changed. When the sheath potential is changed as described above, process parameters for the plasma process are changed. For example, the process parameters are an etch rate, a deposition rate or the like. Hence, the total chuck capacitance between the chuck
5
and the ground terminal must be kept constant to obtain excellent process uniformity.
Meanwhile, the plasma apparatus must be periodically pre-maintained as are other apparatuses used to fabricate semiconductor devices. This pre-maintenance is required since another factor that changes the process parameters is generated by the absorption of a contaminant on the inner wall of the chamber as the process time or the frequency of processing increases. Thus, the plasma apparatus must undergo a pre-maintenance operation of disassembling the plasma apparatus, cleaning the respective component elements including the chamber, and reassembling the disassembled component elements. During the pre-maintenance operation, an operation involving measuring and controlling the gap between the chuck
5
and the gas injection ring
20
using a gage or the like, is performed several times to adjust the gap to within an allowable range. This operation is manually performed, requiring a great amount of time to perform, and making it difficult to accurately adjust the gap to within the allowable range. As a result of this, when the chuck
5
and the gas injection ring
20
are assembled such that they do not have the same center as shown in
FIG. 4B
, a first gap G
1
on the left side of the chuck
5
and a second gap G
2
on the right side of the chuck
5
can be different. In other words, the gap between the chuck
5
and the gas injection ring
20
may not be the same at all positions around the chuck
5
. When the gap between the chuck
5
and the gas injection ring
20
is not uniform as described above, the chuck capacitance may exceed an allowable range. Accordingly, as the total chuck capacitance changes, the uniformity of the process can be degraded.
While a process gas is sprayed into the chamber
10
via the gas injection ring
20
, a physical force due to the pressure or the like of the process gas, is applied to the gas injection ring
20
. In addition, minute vibrations can be generated in the plasma apparatus when it is used for a long time. Thus, even when the gas injection ring
20
is fixed to the chamber
10
by the fixing means
25
, the position of the gas injection ring
20
can change when the plasma process is performed for a long time. When the position of the gas injection ring
20
changes as described above, the gap between the chuck
5
and the gas injection ring
20
changes. Accordingly, chuck capacitance changes, and the total chuck capacitance also changes.
As described above, the total chuck capacitance between the chuck
5
and the grounding terminal of the conventional plasma apparatus cannot be kept constant.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide a plasma apparatus including a capacitance compensator for keeping constant the total chuck capacitance between a ground terminal and a chuck on which a wafer is to be mounted, regardless of a pre-maintenance operation.
It is another object of the present invention to provide a plasma appara
Kim Kiw-sang
Min Young-min
Park In-sung
Alejandro Luz L.
Jones Volentine, L.L.C.
Mills Gregory
Samsung Electronics Co,. Ltd.
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