Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
2001-03-20
2004-09-28
Hassanzadeh, Parviz (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C156S345480, C118S7230MW, C118S7230AN
Reexamination Certificate
active
06797110
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a glass, a component made of the glass and a plasma processing apparatus incorporating the component, and more particularly, to an Al-containing glass having a plasma resistance, a component for an electromagnetic wave-transparent window made of the glass, and a plasma processing apparatus incorporating the component.
2. Description of the Background Art
In the process of manufacturing LSI, LCD or the like, plasma that is generated by externally applying energy to reaction gas is widely used for etching, CVD and the like. In particular, the use of the plasma has been an essential technique in the process of etching. Now, increase in the size of the substrate to be processed with the plasma has been required that the plasma should uniformly be generated over a wider region.
FIGS. 1 and 2
show an example of the apparatus for such a plasma processing. The plasma processing apparatus shown in
FIG. 1
has a rectangular parallelepiped-shaped reactor
31
, which is entirely formed of aluminum. An upper opening of reactor
31
is sealed with a plate
34
such that reactor
31
is maintained gas-tight. Plate
34
is formed of a heat-resistant and microwave-transparent material with a small dielectric loss, e.g. quartz glass (SiO
2
). The upper part of reactor
31
is covered with a rectangular parallelepiped-shaped cover component
40
. A dielectric line
41
is attached to the inside ceiling portion of cover component
40
. Dielectric line
41
is made of a dielectric material such as a fluororesin e.g. Teflon®, a polyethylene resin, a polystyrene resin or the like. Dielectric line
41
has a plate-shaped portion
41
b
and a tapered portion
41
a
that is an extension from the end of plate-shaped portion
41
b
and has an increased thickness. Tapered portion
41
a
is fit into a waveguide
51
connected to cover component
40
. A microwave oscillator
50
is connected to waveguide
51
. Microwave from microwave oscillator
50
is introduced into tapered portion
41
a
of dielectric line
41
via waveguide
51
. The microwave is extended at tapered portion
41
a
and is propagated across the entire dielectric line
41
. The microwave is reflected at the end surface of cover component
40
, which is opposed to waveguide
51
, and then the incident wave and the reflected wave are combined with each other, resulting in a standing wave in dielectric line
41
. A gas introducing tube
35
is inserted into a wall of reactor
31
defining a processing chamber
32
. A stage
33
is provided at the center of the bottom of processing chamber
32
, on which a sample W is placed. Stage
33
is connected to a RF power-supply
37
of several hundreds kHz to ten and several MHz via a matching box
36
. An exhaust vent
38
is provided at the side portion of the bottom of reactor
31
.
In the plasma processing apparatus, the surface of sample W is processed by etching as described below. Processing chamber
32
is evacuated through exhaust vent
38
so that the pressure therein is reduced to a desired pressure, and reaction gas is then supplied from gas introducing tube
35
into processing chamber
32
. Subsequently, microwave oscillator
50
oscillates microwave, which is introduced into dielectric line
41
via waveguide
51
. At that time, the microwave evenly extends in dielectric line
41
by tapered portion
41
a
, resulting in a standing wave. The standing wave forms a leakage electric field at a lower part of dielectric line
41
. The wave passes through plate
34
and enters processing chamber
32
. In processing chamber
32
containing the reaction gas, plasma is generated by the microwave propagated into chamber
32
. A radio frequency is applied from RF power-supply
37
through matching box
36
to stand
33
, so that the surface of sample W is etched. Even if the apparatus has a large diameter of reactor
31
for the process of a large size of sample W, the microwave can be introduced uniformly into the entire region of reaction chamber
31
, so that sample W can be subjected to relatively uniform plasma processing.
In addition to the essential performances of etching and film-forming, the plasma processing apparatus is also required to have some characteristics such as low contamination, reduced particles, long lives of consumable components, low operational cost and easy maintenance. In order to satisfy such characteristics, quartz glass, aluminum, alumina, stainless steel or the like is selected to conform the requirement for the materials of the components constituting the reactor and the internal structure thereof. The quartz glass is useful, among such materials, for the insulating component with low contamination and reduced particle release. For example, in the plasma processing apparatus described above, plate
34
that closes the opening of reactor
31
and separates the microwave-supplying portion from reactor
31
functions as a window for introducing microwave into processing chamber
32
, and such a window has been conventionally made of quartz glass.
However, the quartz glass having good properties as mentioned above easily reacts with fluorine-containing plasma to form SiF
4
. SiF
4
has a low boiling point and is easily vaporized, so that the quartz glass is rapidly etched in the fluorine-containing plasma and hence is worn away. Because the high purity quartz glass used in the process of LSI is expensive, such heavy abrasion would be a factor of a high manufacturing cost. Such heavy abrasion would also increase the frequency of changing the components and the time for such replacement may form a considerable part of the whole manufacturing time. As a result, the processing efficiency may be decreased and the manufacturing cost increased.
As a solution of the problem, Japanese Patent Application No. 4-356922 discloses a component for an electro-discharge and plasma process, which is made of high-purity polycrystalline alumina or high-purity monocrystalline alumina. This component has a microwave-transparent property and a resistance to the plasma derived from CF
4
+O
2
gas.
However, when the alumina component as disclosed in the above publication is used as a microwave-introducing window in the electro-discharge and plasma process, the etching rate may be lowered, or the microwave-introducing window may be damaged due to the distortion of the alumina caused by heat. The inventors of the present invention have investigated the cause of the lowered plasma-processing rate among the problems associated with the use of the alumina microwave-introducing window. As a result, it has been found that the dielectric loss of the alumina is increased (whereas the Q value is decreased) as the temperature of the microwave-introducing window is increased during the plasma processing, so that the transparency to the microwave is reduced, causing the lowered plasma processing rate. It has also been found that a great thermal stress is generated in the alumina plate at a high temperature or with a wide distribution of temperature, resulting in cracks, because of the thermal expansion coefficient of the alumina plate larger than that of quartz glass. Additionally, ceramics such as alumina may contain a sintering agent to aid the formation of the sintered body. Such a sintering agent may constitute a factor in contamination.
SUMMARY OF THE INVENTION
Thus, the present invention is directed to solve the problems described above, and an object of the present invention is to provide a new material having a good plasma resistance.
Particularly, the present invention is directed to solve the problems associated with quartz glass, and another object of the present invention is to provide a component which has not only good properties similar to those of the quartz glass but also a corrosion resistance to plasma especially containing fluorine.
Yet another object of the present invention is to provide an application of the material having such a plasma resistance, and to provide a plasma processing appar
Takano Yuichi
Terao Koichi
Finnegan Henderson Farabow Garrett & Dunner LLP
Hassanzadeh Parviz
Tokyo Electron Limited
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