Electric lamp and discharge devices: systems – Discharge device load with fluent material supply to the... – Plasma generating
Reexamination Certificate
1999-06-24
2001-09-18
Shingleton, Michael B (Department: 2817)
Electric lamp and discharge devices: systems
Discharge device load with fluent material supply to the...
Plasma generating
C174S126300, C174S13300B
Reexamination Certificate
active
06291937
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a high frequency coupler for coupling two high frequency elements, and also to plasma processing apparatus and method which utilize plasma generated by using high frequency electric power for fabrication of electronic devices, such as semiconductors, micro-machines, and the like.
FIG. 7
is a sectional view of an etching apparatus carrying an antenna system plasma source which has been already proposed by us. Referring to
FIG. 7
, when evacuation is carried out by a pump
3
operative as an evacuation device while a predetermined gas is introduced from a gas feeder
2
into a vacuum chamber
1
, and when high-frequency electric power is supplied from a high frequency antenna power source
4
to an antenna
6
on a dielectric window
8
via a matching circuit
5
and a high frequency coupler
107
for coupling the matching circuit
5
to the antenna
6
while a predetermined pressure is maintained in the vacuum chamber
1
, plasma is generated within the vacuum chamber
1
to enable plasma processing, such as etching, depositing, and surface modification, to be carried out with respect to a substrate
10
placed on a substrate electrode
9
. In this case, as
FIG. 7
shows, by supplying high frequency electric power to the substrate electrode
9
from a high frequency power source
11
for the substrate electrode, it is possible to control ion energy that would reach the substrate
10
.
The high frequency coupler
107
is a coupler formed from a copper plate and, in case that the high frequency electric power to be supplied to the antenna is of a large magnitude, plural copper plates, superposed one over another, are used in order to increase the electric current capacity. The reason why a copper plate material comprised of copper plates placed one over another is preferred rather than a copper plate having its thickness merely increased is that high frequency provides a skin effect. That is, a high frequency current tends to flow only in the uppermost surface of a conductor and, therefore, in order to allow a large current flow, it is necessary to increase the surface area of the conductor.
However, the conventional system shown in
FIG. 7
involves the problem of poor plasma uniformity.
The configuration of the copper plate is such that the copper plate is poorly symmetric in relation to the center of the antenna and, therefore, a current distribution will occur on the antenna under the influence of the electric current flowing in the copper plate. That is, the distribution of electric current flowing in the antenna shows such a non-uniformity as illustrated in FIG.
8
. In order to uniformize the distribution of current, it is better that a cylindrical high-frequency coupler is us ed instead of the copper plate. In that case, however, there is a problem that the surface area of the high frequency coupler is too small to allow a large current flow.
Such a phenomenon as above mentioned is not a phenomenon which can be seen only with a plasma processing apparatus carrying a plasma source of antenna system. A similar phenomenon can be seen with a plasma processing apparatus of such a system as shown in
FIG. 9
in which a high frequency electric power is supplied to an opposite electrode
21
and also with a plasma processing apparatus of such a system as shown in
FIG. 10
in which a high frequency electric power is supplied to a substrate electrode
9
thereby to generate plasma.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a high frequency coupler which can exhibit particularly good effect in the construction of a plasma processing apparatus capable of generating uniform plasmas, and to provide a plasma processing apparatus and method which can generate uniform plasmas.
In accomplishing these and other aspects, according to a first aspect of the present invention, there is provided a high frequency coupler for coupling first and second high frequency elements, a section of the coupler cut by a plane perpendicular to a straight line which connects a center of a joint surface between the coupler and the first high frequency element and a center of a joint surface between the coupler and the second high frequency element having a configuration such that the section contains a plurality of line segments arranged radially from an approximately center of the section.
According to a second aspect of the present invention, there is provided a high frequency coupler as set forth in the first aspect, wherein the radially arranged plurality of line segments are generally point-symmetrically arranged in relation to the center of the section of the coupler cut by the plane perpendicular to the straight line which connects the center of the joint surface between the coupler and the first high frequency element and the center of the joint surface between the coupler and the second high frequency element.
According to a third aspect of the present invention, there is provided a high frequency coupler as set forth in the first aspect, wherein the joint surface between the coupler and the first or second high frequency element is a generally circular plane.
According to a fourth aspect of the present invention, there is provided a high frequency coupler as set forth in the first aspect, wherein a tap for screwing-in a bolt is provided at the approximately center of the joint surface between the coupler and the first high frequency element, and a tap for screwing-in a bolt is provided at the approximately center of the joint surface between the coupler and the second high frequency element.
According to a fifth aspect of the present invention, there is provided a high frequency coupler as set forth in the first aspect, wherein a surface portion of the coupler in which a high frequency current flows is comprised of a material having an electric resistivity of not more than 2×10
−8
&OHgr;·m.
According to a sixth aspect of the present invention, there is provided a plasma processing apparatus comprising:
a vacuum chamber;
a gas supply device for supplying gas into the vacuum chamber;
an evacuation device for evacuating an interior of the vacuum chamber;
an electromagnetic wave radiation device such as an antenna or an opposite side positioned electrode for allowing high frequency power to act on the interior of the vacuum chamber;
a high-frequency power source capable of supplying the high frequency power to the electromagnetic wave radiation device;
a matching circuit;
a high frequency coupler for coupling the matching circuit and the electromagnetic wave radiation device; and
a substrate electrode for placing a substrate in the vacuum chamber,
a section of the high frequency coupler cut by a plane perpendicular to a first straight line which connects a center of a joint surface between the high frequency coupler and an output portion of the matching circuit and a center of a joint surface between the high frequency coupler and the electromagnetic wave radiation device having, at a portion where the high frequency coupler contacts the electromagnetic wave radiation device, a configuration such that the section contains a plurality of line segments arranged radially from the approximately center of the section, and the first straight line passing about centrally through the substrate and being positioned on a second straight line in generally perpendicular relation to the substrate.
According to a seventh aspect of the present invention, there is provided a plasma processing apparatus as set forth in the sixth aspect, wherein the radially arranged plurality of line segments are generally point-symmetrically arranged in relation to the center of the section of the coupler cut by the plane perpendicular to the first straight line.
According to an eighth aspect of the present invention, there is provided a plasma processing apparatus as set forth in the sixth aspect, wherein the joint surface between the high frequency coupler and the output portion of the matching circuit or the joint surface bet
Okumura Tomohiro
Watanabe Shozo
Matsushita Electric - Industrial Co., Ltd.
Shingleton Michael B
Wenderoth , Lind & Ponack, L.L.P.
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