Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
1999-01-06
2001-09-18
Dang, Thi (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C118S7230MW, C204S298380
Reexamination Certificate
active
06290807
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and a method for conducting a process such as etching, ashing and depositing on a semiconductor substrate or an LCD glass plate by plasma generated by using microwave energy.
Plasma generated by externally applying an energy to a reaction gas is widely used in manufacture processes for LSIs and LCDs. In particular, the usage of plasma is an indispensable basic technique in a dry etching process and chemical vapor deposition.
FIG. 1
is a side sectional view of a conventional microwave plasma process apparatus and
FIG. 2
is a plan view of the plasma process apparatus of
FIG. 1. A
reactor
31
in the shape of a rectangular box is made from aluminum. The reactor
31
is provided with a microwave introducing window at its upper portion, and the microwave introducing window is airtightly sealed with a sealing plate
34
. The sealing plate
34
is made from a dielectric material, such as quartz glass and alumina, having heat resistance, microwave penetrability and a small dielectric loss.
The reactor
31
is coupled with a cover
40
in the shape of a rectangular box covering the upper portion of the reactor
31
. A dielectric plate
41
is disposed on the ceiling within the cover
40
, and an air gap
43
is provided between the dielectric plate
41
and the sealing plate
34
. The dielectric plate
41
is formed out of a plate of a dielectric material, for example, a fluororesin such as Teflon (registered trademark), a polyethylene resin or a polystyrene resin in a substantially pentagonal shape, obtained by combining a rectangle and a triangle, provided with a projection on its apex. The projection on the apex of the dielectric plate
41
is fit in a waveguide
21
coupled with the cover
40
. The waveguide
21
is connected with a microwave oscillator
20
, so that a microwave oscillated by the microwave oscillator
20
can be guided by the waveguide
21
so as to enter the projection of the dielectric plate
41
.
As described above, the base portion of the projection of the dielectric plate
41
is formed as a taper portion
41
a
in a substantially triangle shape in a plan view. The microwave having entered the projection is expanded in the lateral direction along the taper portion
41
a
and propagated in the entire dielectric plate
41
. The microwave is reflected on the end face of the cover
40
opposing the waveguide
21
, so that the incident wave and the reflected wave can be superimposed so as to generate a standing wave in the dielectric plate
41
.
The inside of the reactor
31
works as a process chamber
32
, and a desired gas is introduced into the process chamber
32
through a gas inlet tube
35
. At the center of the bottom of the process chamber
32
, a table
33
for placing a sample W is disposed, and the table
33
is connected through a matching box
36
with a high frequency power supply
37
. The bottom of the reactor
31
is also provided with an air outlet
38
, so as to exhaust the air within the process chamber
32
through the air outlet
38
.
In conducting an etching process on the surface of the sample W by using this microwave plasma process apparatus, the pressure within the process chamber
32
is decreased down to a desired pressure by exhausting through the air outlet
38
, and then, a reaction gas is supplied to the process chamber
32
through the gas inlet tube
35
. Subsequently, a microwave is oscillated by the microwave oscillator
20
, and the oscillated microwave is introduced into the dielectric plate
41
through the waveguide
21
. At this point, the microwave is uniformly expanded within the dielectric plate
41
owing to the taper portion
41
a
, thereby generating a standing wave in the dielectric plate
41
. This standing wave forms a leakage electric field below the dielectric plate
41
, and the leakage electric field is introduced into the process chamber
32
through the air gap
43
and the sealing plate
34
. In this manner, the microwave is propagated to the process chamber
32
. As a result, plasma is generated in the process chamber
32
, and the surface of the sample W is etched by using the plasma.
The conventional microwave plasma process apparatus includes the taper portion
41
a
projecting from the edges of the sealing plate
34
and the reactor
31
in the horizontal direction in order to uniformly expand the microwave in the dielectric plate
41
. The dimension of the taper portion
41
a
is defined in accordance with the area of the dielectric plate
41
, namely, the dimension of the process chamber
32
. Accordingly, when the conventional microwave plasma process apparatus is to be installed, an additional horizontally extending space is required for the taper portion
41
a
projecting from the edge of the reactor
31
.
In accordance with the dimensional increase of the sample W, there is a demand for a microwave plasma process apparatus including the reactor
31
with a further larger dimension. At the same time, there is a demand that the entire apparatus can be installed in a space as small as possible. However, since the dimension of the taper portion
41
a
of the conventional apparatus is defined in accordance with the dimension of the reactor
31
, the dimension of the taper portion
41
a
increases as the dimension of the reactor
31
increases. Accordingly, the two demands that a microwave plasma process apparatus including a larger reaction vessel
31
is to be installed in a space as small as possible cannot be satisfied at the same time.
BRIEF SUMMARY OF THE INVENTION
The present invention was devised to overcome the aforementioned conventional problems, and an object of the invention is providing a microwave plasma process apparatus which can be minimized in its size, with retaining a large dimension of a reactor included therein, so as to be installed in a small space.
Another object of the invention is providing a microwave plasma process apparatus in which the uniformly process can be executed even when a distance between an antenna and a sample is small.
Still another object of the invention is providing a microwave plasma process apparatus in which the process speed can be improved.
Still another object of the invention is providing a microwave plasma process apparatus in which a usage efficiency of a reaction gas can be improved.
The microwave plasma process apparatus of this invention comprises a chamber being sealed with a sealing member; a gas inlet tube for introducing a gas into the chamber; and an antenna opposing a surface of the sealing member, and the antenna includes a tubular member in a circular shape for propagating the microwaves; an entrance disposed on a circumferential face of the tubular member for introducing the microwaves into the tubular member; and a slit formed in a portion of the tubular member opposing the sealing member.
In the microwave plasma process method of this invention, a plasma process is conducted by using the aforementioned apparatus.
The microwaves entered the antenna from the entrance propagate through the antenna as progressive waves progressing in the mutually reverse directions through the tubular member of the antenna, and come into collision with each other in a position opposing the entrance of the tubular member. Thus, standing waves are generated.
The standing waves allow a current having a maximum value at predetermined intervals to flow in the wall of the tubular member. The slit is formed in the portion of the tubular member opposing the sealing member, and the current causes a potential difference between the inside and the outside of the tubular member at both sides of the slit. An electric field is emitted through the slit to the sealing member owing to this potential difference. In this manner, the microwaves are propagated from the antenna to the sealing member. The microwaves transmit the sealing member and are introduced into the chamber, where plasma is generated by using the microwaves.
In this manner, the microwaves can directly enter the tubular member
Matsumoto Naoki
Nakanishi Toshio
Barnes & Thornburg
Dang Thi
Tokyo Electron Limited
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