Electric lamp and discharge devices: systems – Combined load device or load device temperature modifying... – Distributed parameter resonator-type magnetron
Reexamination Certificate
2002-12-20
2004-03-16
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Combined load device or load device temperature modifying...
Distributed parameter resonator-type magnetron
C315S039550, C315S111510, C315S111210, C118S7230IR, C118S7230AN, C156S345480
Reexamination Certificate
active
06707253
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a matching circuit and a plasma processing apparatus used for manufacturing electronic devices of semiconductors, liquid crystal devices and so on and micro machines.
In manufacturing electronic devices of semiconductors, liquid crystal devices and so on and micro machines, a thin film processing technology by plasma processing has been used.
FIG. 4
shows a typical plasma processing apparatus. A gas supply system
2
is provided on the sidewall of a vacuum vessel
1
. Air discharging is performed by a turbo-molecular pump
4
through an exhaust port
3
provided on a bottom wall while a prescribed gas is supplied to the inside by the gas supply system
2
, and the vacuum vessel
1
is internally kept at a prescribed pressure. A pressure regulating valve
5
for controlling the inside of the vacuum vessel
1
to a prescribed pressure is provided above the exhaust port
3
so as to move up and down. A substrate electrode
7
, on which a substrate
6
to be subjected to plasma processing is placed, is fixed via four props
8
inside the vacuum vessel
1
. The substrate electrode
7
is supplied with a high-frequency power of a frequency of 500 kHz from a high frequency power source
9
for the substrate electrode. An inner chamber
10
is provided particularly around the substrate electrode
7
inside the vacuum vessel
1
, so that the inner wall surface of the vacuum vessel
1
is prevented from becoming dirty due to the plasma processing.
Moreover, a disk-shaped antenna
11
is fixed on the inner surface of the upper wall of the vacuum vessel
1
via a dielectric plate
12
oppositely to the substrate electrode
7
. The lower surface of the antenna
11
is covered with a cover
13
. Around the antenna
11
, a conductor ring
14
is fixed via a dielectric ring
15
on the inner surface of the upper wall of the vacuum vessel
1
. With this arrangement, an annular plasma trap
16
is provided between the conductor ring
14
and the antenna
11
and between the dielectric ring
15
and the dielectric plate
12
. The antenna
11
is provided with a feeder rod
17
that penetrates through the dielectric plate
12
and the upper wall of the vacuum vessel
1
, and the feeder rod
17
is supplied with a high-frequency power of a frequency f=100 MHz from a high-frequency power source
18
for the antenna via a matching circuit
20
by way of a coaxial pipe
19
.
If the substrate electrode
7
and the antenna
11
are supplied with the high-frequency power in a state that the vacuum vessel
1
is internally discharged and filled with a prescribed gas at a prescribed pressure, then plasma is generated in the vacuum vessel
1
, causing the substrate
6
placed on the substrate electrode
7
to be subjected to plasma processing.
The matching circuit
20
is to reduce the power loss by matching the impedance of the antenna
11
with the characteristic impedance of the coaxial pipe
19
that serves as a coaxial line. The matching circuit
20
is constructed of the circuit shown in FIG.
5
. That is, to an input terminal
21
to which the coaxial pipe
19
is connected, one terminal of a first variable capacitor
22
that serves as a first variable reactance element is connected via a copper plate
23
that acts as inductance. The other terminal of the first variable capacitor
22
is grounded via a casing
24
. One terminal of a second variable capacitor
25
that serves as a second variable reactance element is connected to the input terminal
21
via a copper plate
26
that acts as inductance. The other terminal of the second variable capacitor
25
is connected to an output terminal
27
of the matching circuit
20
to which the antenna
11
is connected.
However, the matching circuit
20
of the conventional plasma processing apparatus has had a narrow range in which matching can be achieved. Thus, the matching circuit
20
has been able to secure the matching only on limited discharge conditions even when the discharge conditions of the type and flow rate of gas, the pressure in the vacuum vessel, the high-frequency power and so on have been changed. Moreover, if any of the gas type, the gas flow rate, the pressure in the vacuum vessel and the high-frequency power is changed during the plasma processing, then it sometimes takes about five to ten seconds to the attainment of a matched state when the change in the impedance of the antenna
11
before and after the change is large. If the change in the impedance of the antenna
11
is too large, the matched state has sometimes been unable to be secured. Furthermore, if the frequency of the high-frequency power applied to the antenna
11
is increased, then an excessive current flows through the first variable reactance element
22
and the second variable reactance element
25
of the matching circuit
20
, and an overvoltage is generated across the terminals particularly of the second variable reactance element
25
. This has consequently led to a problem that the temperature has locally risen and the matching state has become unstable.
SUMMARY OF THE INVENTION
The present invention has been accomplished in view of the aforementioned problems and has the object of providing a matching circuit and a plasma processing apparatus, which have a wide range in which matching can be achieved and the matched state of which is stable with respect to a change in the load state.
As a means for solving the aforementioned problems, the present invention provides a matching circuit comprising:
an input terminal;
an output terminal;
a first fixed reactance element;
a second fixed reactance element connected in series to the first fixed reactance element the other terminal of which is grounded;
a first variable reactance element one terminal of which is connected to the input terminal and the other terminal of which is connected to a point between the first fixed reactance element and the second fixed reactance element;
a second variable reactance element one terminal of which is connected to the second fixed reactance element and the other terminal of which is grounded; and
a stripline one terminal of which is connected both to the second variable reactance element and the second fixed reactance element and the other terminal of which is connected to the output terminal.
Assuming that a high-frequency power applied to the input terminal has a wavelength of &lgr; (m), then a sum total D
1
+D
2
of a length D
1
(m) from the output terminal to an antenna connected to the output terminal and a length D
2
(m) of the stripline should preferably satisfy the expression of:
&lgr;/32+&lgr;/2×(
n−
1)≦
D
1
+D
2
≦−&lgr;/
32
+&lgr;/
2
×
n
(n=1, 2, 3, . . . )
It is more preferable that the length D
1
+D
2
satisfies the expression of:
&lgr;/16
≦D
1
+D
2
≦
4
&lgr;/
16
.
The first variable reactance element and the second variable reactance element can each be a variable capacitor. It is preferable that each of the first fixed reactance element and the second fixed reactance element is a coil and the elements are connected in series to constitute one fixed coil. The first fixed reactance element and the second fixed reactance element can each be replaced by a variable reactance element.
As a means for solving the aforementioned problems, the present invention provides a plasma processing apparatus including a vacuum vessel; a gas supply system for supplying a gas into the vacuum vessel; an exhaust system for evacuating the inside of the vacuum vessel; a substrate electrode, which is provided inside the vacuum vessel and on which a substrate to be processed is placed; a substrate electrode high-frequency power source for supplying a high-frequency power to the substrate electrode; an antenna arranged oppositely to the substrate electrode; an antenna high-frequency power source for supplying a high-frequency power to the antenna; and a matching circuit arranged between the antenna and the antenna high-frequency power source, th
Kanda Minoru
Maegawa Yukihiro
Matamura Shiniti
Nakayama Ichiro
Okumura Tomohiro
Philogene Haissa
Wenderoth , Lind & Ponack, L.L.P.
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