Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
1998-12-04
2001-08-07
Huff, Mark F. (Department: 1756)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C204S298060, C204S298080, C204S298340, C204S298380, C118S7230ER, C118S7230MW, C315S111210
Reexamination Certificate
active
06270618
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma processing apparatus.
2. Description of the Related Art
Hitherto, as a plasma processing apparatus, a plasma processing apparatus, as shown in
FIG. 11
, has been known.
A conventional plasma processing apparatus has a matching circuit interposed between a high-frequency power source
1
and a plasma excitation electrode
4
. The matching circuit is a circuit for obtaining impedance matching between the high-frequency power source
1
and the plasma excitation electrode
4
.
The high-frequency power from the high-frequency power source
1
is supplied by a power-supply plate
3
to the plasma excitation electrode
4
through the matching circuit.
The matching circuit is housed in a matching box and the power supply plate
3
is housed in a house
21
.
A shower plate
5
having a number of holes
7
formed therein is provided below the plasma excitation electrode (cathode electrode)
4
, and a space
6
is formed by the plasma excitation electrode
4
and the shower plate
5
. A gas introduction pipe
17
is provided in this space
6
. Gas introduced from the gas introduction pipe
17
is supplied through the holes
7
of the shower plate
5
into a chamber
60
formed by a chamber wall
10
. Reference numeral
9
denotes an insulator which insulates the chamber wall
10
from the plasma excitation electrode (cathode electrode)
4
. Illustration of an exhaust system has been omitted.
Meanwhile, inside the chamber
60
, a wafer susceptor (susceptor electrode)
8
, on which a substrate
16
is placed, which acts also as a plasma excitation electrode is provided, with a susceptor shield
12
being provided around the susceptor electrode
8
. The wafer susceptor
8
and the susceptor shield
12
are movable up and down by a bellows
11
so that the distance between the plasma excitation electrode
4
and the wafer susceptor
8
can be adjusted.
A second high-frequency power source
15
is connected to the wafer susceptor
8
through the matching circuit housed inside a matching box
14
and a shaft
13
. The chamber and the susceptor shield
12
are at the same electrical potential in terms of direct current. In
FIG. 11
, reference numerals
61
a
and
61
b
each denote a resonance circuit, which acts as a band eliminator or a filter.
A case is considered in which, for example, high-frequency power of f
1
=13.56 MHz is supplied to the plasma excitation electrode
4
and high-frequency power of f
2
=100 MHz is supplied to the susceptor electrode
8
.
The band eliminator
61
b
used for the susceptor electrode
8
is a series circuit of LC as shown in
FIG. 11
, and if
2
&pgr;f
1
=1/(
L
2
C
2
)
½
is set, a series resonance state is reached at a resonance frequency of f
1
, the impedance becomes a local minimum, and only a high-frequency wave of f
1
can be selected and supplied to the susceptor electrode
8
, making it possible to generate plasma in a state in which it is trapped between the plasma excitation electrode
4
and the susceptor electrode
8
. With respect to f
1
=13.56 MHz, the susceptor electrode
8
is nearly completely short-circuited to a ground.
FIG. 12
shows another conventional plasma processing apparatus.
In the plasma processing apparatus shown in
FIG. 12
, a shower plate
5
is not used, and the cathode electrode
4
, which is a plasma excitation electrode, and the susceptor electrode
8
directly oppose each other. A shield
20
is provided around the rear surface of the cathode electrode
4
. The remaining construction is the same as that of the plasma processing apparatus shown in FIG.
1
.
In the conventional plasma processing apparatus, the impedance of a band eliminator is designed so as to generate plasma in a state in which it is trapped efficiently between the plasma excitation electrode
4
and the susceptor electrode
8
. That is, the impedance is designed in such a manner as to be fixed so as to efficiently perform film formation.
In this regard, unlike during film formation, when cleaning of the chamber is performed, it is preferable that plasma be generated in such a manner as to be diffused over the entire chamber. In that case, the impedance with respect to the frequency f
1
is preferably made a local maximum point. That is, it is preferable that a parallel resonance state be reached.
There is another case in which, as the value of f
1
, a frequency other than 13.56 MHz described above is used.
However, in the conventional plasma processing apparatus, since the impedance of a band eliminator is designed in such a manner as to be fixed in accordance with the frequency used, when cleaning of the chamber is desired to be performed or when another frequency is desired to be used, this must be performed after the band eliminator is replaced with another one.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a plasma processing apparatus which solves the problems of the conventional technology and which does not require the replacement of a band eliminator according to a frequency to be used. Another object of the present invention is to provide a plasma processing apparatus which is capable of performing chamber cleaning without replacing a band eliminator.
To achieve the above-mentioned objects, the present invention provides a plasma processing apparatus, comprising: a resonance circuit for causing series resonance with a microwave circuit formed of at least a susceptor electrode and a processing chamber in order to trap plasma between a plasma excitation electrode and the susceptor electrode when the surface of a workpiece placed on the susceptor electrode is processed by plasma generated between the plasma excitation electrode and the susceptor electrode, which are provided inside the processing chamber; and for causing parallel resonance with the microwave circuit in order to diffuse plasma inside the processing chamber when performing plasma cleaning.
The above and further objects, aspects and novel features of the invention will become more apparent from the following detailed description when read in connection with the accompanying drawings.
REFERENCES:
patent: Re. 34106 (1992-10-01), Ohmi
patent: 4464223 (1984-08-01), Gorin
patent: 5248371 (1993-09-01), Maher et al.
patent: 5433813 (1995-07-01), Kuwabara
Fukuda Koichi
Kasama Yasuhiko
Kim Sung Chul
Nakano Akira
Ohmi Tadahiro
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Chacko-Davis Daborah
Huff Mark F.
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