Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – Having glow discharge electrode gas energizing means
Reexamination Certificate
2001-07-10
2004-04-27
Alejandro-Mulero, Luz (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
Having glow discharge electrode gas energizing means
C118S7230ER
Reexamination Certificate
active
06726803
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates principally to a plasma generating apparatus used in fabricating semiconductor devices, liquid crystal display panels and solar cells and particularly in processes of etching, ashing, thin film growth by chemical vapor deposition (CVD), sputtering, surface modification and chamber cleaning, and more specifically to a plasma generating apparatus of generating plasma by applying high-frequency power to gas for plasma generating, and particularly to technology for retarding thermal deterioration of a discharge tube. However, an application subject of a plasma generating apparatus in accordance with the present invention is not intended to be limited to the fabrication of semiconductor devices and is widely applicable for any desired objects.
In
FIG. 18
, reference numeral
101
indicates an insulating discharge tube, numeral
102
an insulating cooling medium flow tube, numeral
103
an upper flange for supporting a discharge tube, numeral
104
a lower flange for supporting a discharge tube, numeral
104
a
a cooling medium inlet, numeral
103
a
a cooling medium outlet, numeral
105
a gas introduction flange, numeral
105
a
a gas induction port for plasma, numeral
106
a flange for mounting to a device, numeral
106
a
a plasma discharge port, numeral
107
an induction coil, numeral
108
a high-frequency power supply, numerals
109
to
111
O-rings, numeral
112
a plasma generating space and numeral
113
a cooling medium flow space.
The outer periphery of the discharge tube
101
formed cylindrically is enveloped with the cooling medium flow tube
102
and the upper flange
103
for supporting a discharge tube is fitted externally to be fixed to the top end of the discharge tube
101
and the cooling medium flow tube
102
with O-rings
109
,
110
, respectively, interposed, and the lower flange
104
for supporting a discharge tube is fitted externally to be fixed to the bottom end of the discharge tube
101
and the cooling medium flow tube
102
with O-rings for vacuum-sealing
109
,
110
, respectively, interposed, and a double tube structure is constructed through such a fitting construction. In this double tube structure, the discharge tube
101
and the cooling medium flow tube
102
are coaxial, and the annular cooling medium flow space
113
is formed between both. The lower flange
104
for supporting a discharge tube is provided with the cooling medium inlet
104
a
communicating with the cooling medium flow space
113
, and the upper flange
103
for supporting a discharge tube is provided with the cooling medium outlet
103
a
communicating with the cooling medium flow space
113
. The gas introduction flange
105
which almost blocks the top end opening of the discharge tube
101
is made to abut on and fixed to the upper flange
103
for supporting a discharge tube with the O-rings
111
for vacuum-sealing interposed. The gas introduction port for plasma
105
a
is provided along a central axis of the gas introduction flange
105
in a state of communicating with the plasma generating space
112
of the discharge tube
101
. The flange
106
for mounting to a device is made to abut on and fixed to the lower flange
104
for supporting a discharge tube in a state of communicating with the plasma generating space
112
of the discharge tube
101
with the O-rings
111
interposed. The induction coil
107
is wound on an outside of the outer cooling medium flow tube
102
constituting the double tube structure, and the induction coil
107
is connected to the high-frequency power supply
108
. Further, an impedance matching device, not shown, is interposed between the induction coil
107
and the high-frequency power supply
108
.
A plasma generating apparatus constructed as described above is used in a state of being attached to a plasma processing chamber, not shown, at the flange
106
for mounting to a device. Interior space of the plasma processing chamber and the plasma generating space
112
of the plasma generating apparatus is evacuated by evacuating the plasma processing chamber of air. Then, gas for plasma generation (discharging gas) is supplied from the gas introduction port for plasma
105
a
toward the plasma generating space
112
and high-frequency power is supplied to the induction coil
107
by actuating the high-frequency power supply
108
, and a high-frequency electromagnetic field is generated in the plasma generating space
112
. Simultaneously, a cooling medium is supplied from the cooling medium inlet
104
a
located on the lower side, is moved upward in the cooling medium flow space
113
and is discharged from the cooling medium outlet
103
a.
The gas for plasma generation flows into the plasma generating space
112
, and plasma ignition due to high-frequency discharge occurs in a small region of the flowing gas by action of the high-frequency electromagnetic field upon the gas for plasma generation. Resulting from the plasma ignition occured in a small region, plasma generation is spread almost across the whole of the gas flowing in the plasma generating space
112
. The gas which is ionized to plasma in the plasma generating space
112
in this manner, i.e., plasma flows from the plasma discharge port
106
a
of the flange
106
for mounting to a device into the plasma processing chamber, not shown, and performs plasma processing, such as etching and ashing for semiconductor wafer and liquid crystal substrate, in the plasma processing chamber.
The plasma which is generated in the plasma generating space
112
becomes a high temperature. The discharge tube
101
forms the plasma generating space
112
which is a space for ionizing the gas for plasma generation being introduced from the gas introduction port for plasma
105
a
to plasma. Accordingly, the discharge tube
101
is raised in temperature due to contact with plasma of a high temperature. To limit the temperature rise within a predetermined range, heat exchange is conducted by flowing the cooling medium through the cooling medium flow space
113
surrounding the outer periphery of the discharge tube
101
.
Though the discharge tube
101
is cooled as described above, it is inevitable that temperature difference occurs between the face of the inner circumference of the discharge tube
101
, exposed to plasma of a high temperature, and the face of the outer periphery of the discharge tube
101
, contacting with the cooling medium. Further, generated plasma of high temperature is localized in some cases, and so temperature difference is developed in the direction of a tube axis and in the circumferential direction in the discharge tube
101
as well. Thermal deformation is produced in the discharge tube
101
resulting from such temperature difference.
In a plasma generating apparatus of this sort of high-frequency discharge of inductive coupling type in which induction coils are arranged on an outer periphery of a discharge tube for a discharge tube for flowing the gas for plasma generation, the following conditions are required. That is, since a high-frequency electromagnetic field should be formed in the plasma generating space
112
of the discharge tube
101
by high-frequency power supplied from the induction coils
107
arranged outside of the discharge tube
101
, the discharge tube
101
should be made from material other than a conductor, i.e.,an insulator (inductor) in order not to form electromagnetic shielding. The cooling medium flow tube
102
located at an outer periphery of the discharge tube
101
should also be of insulator. As such an insulator, there are, for instance, quartz, high purity alumina, aluminum nitride, glass and sapphire. Cooling medium flowing through the cooling medium flow space
113
is preferably a substance which does not absorb high-frequency power applied as far as possible, as well.
As described above, thermal deformation tends to be easily produced in the discharge tube
101
, but since the discharge tube
101
is made from insulator, it has low thermal conductivity and
Amadatsu Shigeki
Kondo Kazuki
Minomo Shoichiro
Taniguchi Michio
Alejandro-Mulero Luz
Daihen Corporation
Jordan and Hamburg LLP
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