Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
2001-02-06
2004-09-28
Mills, Gregory (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C156S345410
Reexamination Certificate
active
06796268
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a microwave plasma processing system which is designed to produce plasma in a processing vessel by microwaves introduced from an antenna. More specifically, the invention relates to the improvement of a wave guiding structure of the antenna.
2. Description of the Related Art
FIG. 5
shows an example of a conventional microwave plasma processing system. The microwave plasma processing system shown in
FIG. 5
comprises a processing vessel
1
having a transmission window
10
capable of transmitting microwaves. On the top of the transmission window
10
of the processing vessel
1
, a microwave antenna
102
is mounted.
The antenna
102
serves as a thin cylindrical waveguide, and the bottom thereof is formed with a plurality of slots
106
which are appropriately distributed. The central portion of the antenna
102
is connected to a coaxial line
104
. The coaxial line
104
comprises an inner conductor
104
a
and an outer conductor
104
b
. Through the coaxial line
104
, microwaves are supplied to the antenna
102
from a microwave supply source (not shown).
The microwaves supplied to the antenna
102
through the coaxial line
104
are radiated downwards from the slots
106
while being propagated outwardly in radial directions from the central portion of the antenna
102
. When the microwaves reflect on the outer peripheral portion of the antenna
102
to be returned, the microwaves traveling outwardly and inwardly in radial directions interfere with each other to produce standing waves.
The microwave plasma processing system shown in
FIG. 5
comprises a supporting table
12
provided on the bottom of the processing vessel
1
. In the bottom of the processing vessel
1
corresponding to the surrounding of the supporting table
12
, an exhaust port
13
for evacuating the interior of the processing vessel
1
is formed. At an appropriate position in the upper portion of the processing container
1
, an introducing pipe
14
for introducing a process gas or the like is provided.
The microwave plasma processing system is designed to produce the plasma of the process gas with microwaves, which are introduced from (the slots
106
of) the antenna
102
, in the processing vessel
1
which is held at a predetermined degree of vacuum. With the produced plasma, various intended plasma processes, such as deposition or etching processes, can be carried out with respect to an object W to be processed (e.g., a semiconductor wafer or a LDC substrate) on the supporting table
12
.
In the above-described microwave plasma processing system, there is the following problem. That is, because of the structure that microwaves are radially propagated in the antenna
102
, the radial distribution of the microwaves introduced into the processing vessel
1
from the antenna
102
is difficult to be uniform. For that reason, there is a problem in that the uniformity of the plasma processing for the object W to be processed in the processing vessel
1
decreases.
In accordance with processing conditions, there are some cases where it is not the best to simply obtain the radially uniform intensity of microwaves in the antenna
102
in order to improve the uniformity of the plasma process with respect to the object W to be processed. In such cases, it is required that the radial distribution of microwaves introduced into the processing vessel from the antenna can be optimally set in accordance with processing conditions.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to eliminate the aforementioned problems and to provide a microwave plasma processing system capable of optimally setting the radial distribution of microwaves, which are introduced into a processing vessel from an antenna, in accordance with processing conditions.
In order to accomplish the aforementioned and other objects, according to the present invention, there is provided a microwave plasma processing system comprising: a processing vessel; an antenna for introducing microwaves into the processing vessel; a microwave supply source for supplying the microwaves to the antenna; and a connecting waveguide for connecting the microwave supply source to the antenna, wherein a plasma is produced in the processing vessel by the microwaves introduced from the antenna, the antenna having a plurality of substantially ring-shaped antenna waveguides which are substantially concentrically arranged, each of the antenna waveguides comprising a rectangular waveguide having a wall in which a plurality of slots are formed at intervals, the proximal end portion of each of the antenna waveguides being connected to the connecting waveguide.
According to the present invention, there is also provided a microwave plasma processing system comprising: a processing vessel having a microwave transmittable top wall; an antenna mounted on the top wall of the processing vessel; a microwave supply source for supplying said microwaves to the antenna; and a connecting waveguide for connecting the microwave supply source to the antenna, wherein a plasma is produced in the processing vessel by the microwaves introduced from the antenna, the antenna having a plurality of substantially ring-shaped antenna waveguides which are substantially concentrically arranged, each of the antenna waveguides comprising a rectangular waveguide having a bottom wall in which a plurality of slots are formed at intervals, the proximal end portion of each of the antenna waveguides being connected to the connecting waveguide.
According to these plasma processing systems, it is possible to change the intensity of microwaves by adjusting the dimension of the cross section of each of the antenna waveguides and adjusting the dimension of each of the slots and the interval between adjacent slots every antenna waveguide. Therefore, the radial distribution of microwaves introduced into the processing vessel from the antenna can be optimally set in accordance with processing conditions. Thus, for example, it is possible to remarkably improve the uniformity of a plasma process in the processing vessel.
In the above-described plasma processing systems, at least one of the antenna waveguides of the antenna is preferably provided with aperture variable device for varying the size of an aperture at the proximal end portion. Thus, the intensity of microwaves distributed to a corresponding one of the antenna waveguides can be adjusted by varying the dimension of the aperture in the proximal end portion of the corresponding antenna waveguide by the aperture variable device. Therefore, the radial distribution of microwaves introduced into the processing vessel from the antenna can be freely changed in accordance with the variation in process conditions.
The terminal end portion of each of the antenna waveguides of the antenna may be closed with a conductor or a microwave absorber.
The connecting waveguide may extend to the proximal end portion of the innermost one of the antenna waveguides in a substantially radial direction with respect to each of the antenna waveguides. In such a case, the terminal end portion of the connecting waveguide may be closed with a conductor or a microwave absorber.
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Crowell Michelle
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Mills Gregory
Tokyo Electron Limited
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