U.S. patent application number 09/756103 was filed with the patent office on 2001-12-27 for plasma dry scrubber.
Invention is credited to Choi, Dae-Kyu.
Application Number | 20010055552 09/756103 |
Document ID | / |
Family ID | 19674298 |
Filed Date | 2001-12-27 |
United States Patent
Application |
20010055552 |
Kind Code |
A1 |
Choi, Dae-Kyu |
December 27, 2001 |
Plasma dry scrubber
Abstract
A plasma dry scrubber for scrubbing gas comprises a plasma
generator, an impedance matching unit, and an RF generator. A high
frequency signal generated by the RF generator is fed, via the
impedance matching unit, to first and second antennas, which are
provided at the upper and lower parts, respectively, of the plasma
generator. Gas flowing into the plasma generator is decomposed by
means of magnetic fields generated by the first and second
antennas, and the decomposed gas is discharged to a vacuum pump via
a gas outlet pipe. The magnetic fields generated by first and
second antennas are distributed more uniformly in a plasma
generating chamber so that plasma discharge is accomplished
uniformly. Furthermore, the non-conductive isolating plates are
made of ceramic or quartz so as to isolate the first and second
antennas, respectively, from the plasma generating chamber. The
thickness of the isolating plates may be altered, if required,
whereby any damage to the plasma dry scrubber, due to the pressure
from a vacuum pump, is prevented, even if it is used for a long
time.
Inventors: |
Choi, Dae-Kyu; (Seoul,
KR) |
Correspondence
Address: |
Robert E. Bushnell
Suite 300
1522 K Street, N.W.
Washington
DC
20005
US
|
Family ID: |
19674298 |
Appl. No.: |
09/756103 |
Filed: |
January 9, 2001 |
Current U.S.
Class: |
422/186.29 |
Current CPC
Class: |
B01D 53/32 20130101;
H01J 37/32844 20130101; H01J 37/32082 20130101; Y02C 20/30
20130101; H05H 1/46 20130101; B01D 2259/818 20130101 |
Class at
Publication: |
422/186.29 |
International
Class: |
B01J 019/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2000 |
KR |
35786/2000 |
Claims
What is claimed is:
1. A plasma dry scrubber in which introduced gas is decomposed in a
plasma state so that the gas is scrubbed, said scrubber comprising:
a plasma generator for generating the plasma; a radio frequency
(RF) generator for generating a high frequency power supply signal;
and an impedance matching unit disposed between the plasma
generator and the RF generator for receiving and impedance matching
the high frequency power supply signal from the RF generator, and
for feeding the impedance-matched high frequency power supply
signal as an output; wherein said plasma generator comprises: first
and second antennas for receiving the impedance-matched high
frequency power supply signal from the impedance matching unit, and
for generating a plasma; a housing having a gas inlet port through
which gas to be scrubbed is introduced, a gas outlet port through
which the scrubbed gas is discharged, a plasma generating chamber
formed between the gas inlet port and the gas outlet port, and
first and second receiving units provided at upper and lower parts,
respectively, of the housing for receiving the first and second
antennas, respectively; and first and second isolating plates
mounted in the first and second receiving units, respectively, for
isolating the first and second antennas, respectively, from the
plasma generating chamber.
2. The plasma dry scrubber as claimed in claim 1, wherein the first
and second isolating plates are made of one of ceramic and
quartz.
3. The plasma dry scrubber as claimed in claim 1, wherein the first
and second antennas are connected electrically in series with each
other so that magnetic fields are generated in same directions.
4. The plasma dry scrubber as claimed in claim 1, wherein the first
and second antennas are connected electrically in parallel with
each other so that magnetic fields are generated in opposite
directions.
5. The plasma dry scrubber as claimed in claim 1, wherein the first
and second antennas have spiral configurations.
6. The plasma dry scrubber as claimed in claim 1, wherein the RF
generator comprises a frequency-variable high frequency
generator.
7. The plasma dry scrubber as claimed in claim 1, wherein the
impedance matching unit comprises a plurality of variable
capacitors.
8. The plasma dry scrubber as claimed in claim 1, further
comprising first and second brackets mounted between said first and
second antennas, respectively, and said first and second isolating
plates, respectively.
9. The plasma dry scrubber as claimed in claim 8, further
comprising first and second O-rings disposed between said first and
second isolating plates, respectively, and said first and second
receiving units, respectively.
10. The plasma dry scrubber as claimed in claim 8, further
comprising first and second covers disposed on a side of said first
and second antennas, respectively, remote from said first and
second receiving units, respectively.
11. In a plasma dry scrubber in which introduced gas is decomposed
in a plasma state so that the gas is scrubbed, a plasma generator
for generating the plasma, said plasma generator comprising: first
and second antennas for receiving a high frequency power supply
signal, and for generating a plasma; a housing having a gas inlet
port through which gas to be scrubbed is introduced and a gas
outlet port through which the scrubbed gas is discharged; a plasma
generating chamber formed between the gas inlet port and the gas
outlet port; first and second receiving units provided above and
below, respectively, the plasma generating chamber for receiving
the first and second antennas, respectively; and first and second
isolating plates mounted in the first and second receiving units,
respectively, for isolating the first and second antennas,
respectively, from the plasma generating chamber.
12. In the plasma dry scrubber as claimed in claim 11, further
comprising an impedance matching unit for receiving and impedance
matching the high frequency power supply signal, and for feeding
the impedance-matched high frequency power supply signal to the
first and second antennas.
13. In the plasma dry scrubber as claimed in claim 11, wherein the
impedance matching unit comprises a plurality of variable
capacitors.
14. In the plasma dry scrubber as claimed in claim 11, wherein the
first and second isolating plates are made of one of ceramic and
quartz.
15. In the plasma dry scrubber as claimed in claim 11, wherein the
first and second antennas are connected electrically in series with
each other so that magnetic fields are generated in same
directions.
16. In the plasma dry scrubber as claimed in claim 11, wherein the
first and second antennas are connected electrically in parallel
with each other so that magnetic fields are generated in opposite
directions.
17. In the plasma dry scrubber as claimed in claim 11, wherein the
first and second antennas have spiral configurations.
18. In the plasma dry scrubber as claimed in claim 11, wherein the
high frequency power supply signal is generated by a frequency
variable high frequency generator.
Description
[0001] This application makes reference to, incorporates the same
herein, and claims all benefits accruing under 35 U.S.C. .sctn.119
from my application PLASMA DRY SCRUBBER filed with the Korean
Industrial Property Office on Jun. 27, 2000 and there duly assigned
Serial No. 35786/2000.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present invention relates to a dry scrubber and, more
particularly, to a plasma dry scrubber for scrubbing the gas
exhausted during a semiconductor manufacturing process by means of
physical and chemical decomposition actions using plasma.
[0004] 2. Description of the Prior Art
[0005] Semiconductor devices are manufactured via a plurality of
processes. Among semiconductor manufacturing processes, especially
a diffusion process and an etching process are repeated frequently.
After completion of the processes, gas remaining in a process
chamber is discharged to the outside via a discharging system.
However, among gases used in the semiconductor manufacturing
process, such as the diffusion process, etching process or the
like, there exist noxious gases, such as CF4, CHF3, C2F6, or the
like. On this account, it is required that the gas discharged
through the discharging system be subject to an additional cleaning
process. For that purpose, dry or wet scrubbers are used at
present.
[0006] Generally, in accordance with the decomposition process,
such as heat decomposition or plasma decomposition, a gas scrubber
is used for dry scrubbing. It is known that it is difficult to
decompose noxious gases effectively below the allowed concentration
by gas scrubbing according to the plasma process. The reason for
such a disadvantage is as follows:
[0007] The plasma process is divided into an ICP (inductive coupled
plasma) process and a CCP (capacitive coupled plasma) process in
accordance with the plasma generation configuration. The ICP
process has a drawback in that the uniformity of the magnetic field
is not maintained due to its constructional characteristic. Also,
the capability of gas decomposition is reduced if the diameter of
the discharging pipe is increased. Particularly, in the ICP
process, an electric discharge tube made of quartz is arranged
between the process chamber and the vacuum pump, and is reduced
gradually in thickness when it is used for a long time. Thus, in
some cases, there is a possibility that the electric discharge tube
becomes damaged due to the pressure of the vacuum pump. The CCP
process has a drawback in that ion particles are generated in the
process chamber.
SUMMARY OF THE INVENTION
[0008] Accordingly, it is an object of the present invention to
eliminate the drawbacks as mentioned above by providing a plasma,
dry scrubber capable of generating the plasma uniformly in the gas
scrubbing application using the plasma, and of increasing the
intensity of the magnetic field so that the capability of the gas
decomposition is enhanced.
[0009] It is another object of the present invention to provide a
plasma dry scrubber which does not get damaged due to the pressure
from a vacuum pump.
[0010] To accomplish the aforementioned objects, in accordance with
one aspect of the present invention, a plasma dry scrubber
decomposes the introduced gas in a plasma state so that the gas is
scrubbed, and comprises: a plasma generator having first and second
antennas for generating the plasma; an RF generator for generating
a high frequency power supply; and an impedance matching unit,
corrected between the first and second plasma generating antennas
and the RF generator, for receiving and impedance matching the high
frequency power supply signal generated by the RF generator, and
then feeding the impedance matched signal to the first and second
antennas.
[0011] The plasma, generator includes: a housing having a gas inlet
port through which gas to be scrubbed is introduced; a gas outlet
port through which the scrubbed gas is discharged; a plasma
generating chamber formed between the gas inlet port and the gas
outlet port; first and second receiving units provided at upper and
lower parts, respectively, of the plasma generator for receiving
the first and second antennas, respectively; and first and second
isolating plates mounted on the first and second receiving units,
respectively, for isolating the first and second antennas from the
plasma generating chamber.
[0012] In a preferred embodiment, the first and second isolating
plates are made of ceramic or quartz. The first and second antennas
have spiral configurations, and the first and second antennas are
connected electrically in series with each other or electrically in
parallel with each other so that magnetic fields are generated in
the same or opposite directions, respectively.
[0013] In a preferred embodiment, the RF generator is a
frequency-variable high frequency generator. The impedance matching
unit comprises a plurality of variable capacitors.
[0014] According to the present invention, magnetic fields are
generated by the first and second antennas mounted on the upper
part and the lower part, respectively, of the plasma generator, and
are distributed more uniformly in a plasma generating chamber so
that plasma discharge is accomplished uniformly. Also,
non-conductive isolating plates made of ceramic or quartz are
provided for isolating the first and second antennas from the
plasma generating chamber. The plates are sufficiently thick to
bear up against the pressure from a vacuum pump.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] A more complete appreciation of the invention, and many of
the attendant advantages, thereof, will be readily apparent as the
same becomes better understood by reference to the following
detailed description when considered in conjunction with the
accompanying drawings in which like reference symbols indicate the
same or similar components, wherein:
[0016] FIG. 1 is a perspective view showing a plasma dry scrubber
according to a preferred embodiment of the present invention;
[0017] FIG. 2 is a circuit diagram showing the construction of a
plasma dry scrubber according to a preferred embodiment of the
present invention;
[0018] FIG. 3 is an exploded perspective view of the plasma
generator of FIG. 1;
[0019] FIG. 4 is a cross sectional view of the plasma generator of
FIG. 1; and
[0020] FIG. 5 thru FIG. 8 are illustrative views showing magnetic
fields generated by the first and second antennas of FIG. 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] FIG. 1 is a perspective view showing a plasma dry scrubber
according to a preferred embodiment of the present invention, and
FIG. 2 is a circuit diagram showing the construction of a plasma
dry scrubber according to a preferred embodiment of the present
invention.
[0022] Referring to the drawings, a plasma dry scrubber 30 mainly
comprises a plasma generator 32, an impedance matching unit 34, and
an RF generator 36. The plasma generator 32 is connected to a gas
inlet pipe 15, which is connected to a process chamber 10. The
plasma generator 32 is also connected to a gas outlet pipe 25,
which is connected to a vacuum pump 20. As will be described in
more detail, the plasma generator 32 is provided, at upper and
lower parts thereof, with first and second antennas, respectively
(not shown in FIGS. 1 and 2). The first and second antennas are
connected to the RF generator 36 via the impedance matching unit
34. The is impedance matching unit 34 includes two variable
capacitors C1 and C2 for impedance matching. The RF generator 36
comprises a frequency-variable high frequency generator.
[0023] A high frequency signal generated by the RF generator 36 is
fed to the first and second antennas via the impedance matching
unit 34. Gas flowing into the plasma generator 32 from the gas
inlet pipe 15 via the process chamber 10 is decomposed by means of
magnetic fields generated by the first and second antennas. The
decomposed gas is discharged to the vacuum pump 20 via the gas
outlet pipe 25.
[0024] The construction of the plasma generator will be now
described in more detail with reference to FIG. 3 and FIG. 4. FIG.
3 is an exploded perspective view of the plasma generator of FIG.
1, and FIG. 4 is a cross sectional view of the plasma generator of
FIG. 1.
[0025] Referring to the drawings, the plasma generator 32 is
provided, at upper and lower parts thereof, with first and second
antennas 42 and 82, respectively. The first and second antennas 42
and 82, respectively, have spiral configurations. Between the gas
inlet pipe 15 and the gas outlet pipe 25, a housing 60 of the
plasma generator 32 is disposed. The housing 60 comprises a gas
inlet port 65 through which gas to be scrubbed is introduced, a gas
outlet port 64 through which the scrubbed gas is discharged, a
plasma generating chamber 68 formed between the gas inlet port 65
and the gas outlet port 64, and first and second receiving units 61
and 62, respectively, provided at the upper and the lower parts,
respectively, of the system for receiving the first and second
antennas 42 and 82, respectively.
[0026] Inside the first receiving unit 61, first antenna 42 is
mounted. It is isolated from the plasma generating chamber 68 by a
first isolating plate 46 made of non-conductive materials, such as
ceramic or quartz. The first isolating plate 46 is engaged with a
first bracket 44, and is mounted on the first receiving unit 61 by
means of a plurality of bolts 52, with a first O-ring 48
therebetween. A first cover 40 is engaged with the first receiving
unit 61 by means of a plurality of bolts 50. The first antenna 42
is connected to the impedance matching unit 34 through a groove 66
of the first receiving unit 61.
[0027] Inside the second receiving unit 62, the second antenna 82
is mounted and is isolated from the plasma generating chamber 68 by
a second isolating plate 86 made of non-conductive materials, such
as ceramic or quartz. The second isolating plate 86 is engaged with
a second bracket 84, and is mounted to the second receiving unit 62
by means of a plurality of bolts 72, with a second O-ring 88
therebetween. A second cover 80 is engaged with the second
receiving unit 62 by means of a plurality of bolts 70. The second
antenna 82 is connected to the impedance matching unit 34 through a
groove 67 of the second receiving unit 62.
[0028] FIG. 5 thru FIG. 8 are illustrative views showing magnetic
fields generated by the first and the second antennas,
respectively, of FIG. 2.
[0029] As shown in FIG. 5 and FIG. 6, the first and second antennas
42 and 82 are each configured in such a way that the magnetic
fields are generated in the same directions, that is they are
connected electrically to each other in series, as shown in FIG. 5.
In addition, they are connected electrically in parallel to each
other, as seen in FIG. 6. In this manner, as the first and second
antennas 42 and 82 generate magnetic fields in the same directions,
the intensity of the magnetic fields thereof is increased two times
more than that of the magnetic field generated by a single antenna.
By virtue of the increased magnetic field, the decomposition effect
of the gas which passes through the plasma generating chamber 68 is
enhanced.
[0030] As shown in FIG. 7 and FIG. 8, the first and second antennas
42 and 82 are configured in such a way that the magnetic fields are
generated in the opposite directions, they are connected
electrically in series to each other, as seen in FIG. 7. In
addition, they are connected electrically in parallel to each
other, as seen in FIG. 8. In this manner, as with the first and
second antennas 42 and 82, respectively, the program generates
fields in opposite directions. Therefore, the decomposition effect
of the gas which passes through the plasma generating chamber 68 is
enhanced.
[0031] In this way, the connection of the first and second antennas
42 and 82, respectively, may be altered if required. For example,
if there is a large gap between the first antenna 42 and the second
antenna 82, the magnetic fields are generated in the same
directions; and, if there is a small gap between the first antenna
42 and the second antenna 82, the magnetic fields are generated in
the opposite directions, so that the capability of the gas
decomposition is more enhanced.
[0032] According to the present invention as described above, it is
possible to generate the plasma uniformly in the scrubber, and to
increase the intensity of the magnetic field, so that the
capability of the gas decomposition is enhanced. Furthermore, it is
possible to alter the thickness of the non-conductive isolating
plate made of ceramic or quartz to isolate the first and second
antennas from the plasma generating chamber, if required, whereby
any damage to the plasma dry scrubber, due to the pressure from a
vacuum pump, is prevented, even if it is used for a long time.
[0033] Although there has been described above the construction and
operation of the plasma dry scrubber according to a preferred
embodiment of the present invention with reference to the drawings,
such description is for illustrative purposes only. Accordingly,
any and all modifications or variations which may occur to those
skilled in the art should be considered to be within the scope of
the invention.
* * * * *