Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
2000-10-27
2003-11-25
Hassanzadeh, Parviz (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C118S7230MW, C315S111210
Reexamination Certificate
active
06652709
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma processing apparatus and a plasma processing method, and more particularly to a microwave plasma processing apparatus and method utilizing an improved system for introducing microwaves.
2. Related Background Art
As plasma processing apparatuses that use microwaves as an excitation source for plasma generation, there have been known the etching apparatus, the ashing apparatus, the CVD apparatus, the doping apparatus, the cleaning apparatus, the surface modifying apparatus and the like that are used for producing semiconductor devices.
The etching of an article to be processed (hereinafter, simply referred to as “article” as occasion demands) using a microwave plasma etching apparatus is carried out, for example, as follows. An etchant gas is introduced into a plasma generation chamber of the microwave plasma etching apparatus, and a microwave energy is simultaneously introduced therein to excite and decompose the etchant gas, thereby etching a surface of the article.
Furthermore, the ashing of an article using a microwave plasma ashing apparatus is carried out, for example, as follows. An ashing gas is introduced into a plasma generation chamber of the microwave plasma ashing apparatus, and a microwave energy is simultaneously introduced thereinto to excite and decompose the ashing gas, thereby ashing an organic matter such as a photoresist, etc. existing on a surface of the article.
Moreover, the film formation on an article using a microwave plasma CVD apparatus is carried out, for example, as follows. A reactive gas is introduced into a plasma generation chamber of a microwave plasma CVD apparatus, and a microwave energy is simultaneously introduced thereinto to excite and decompose the reactive gas, thereby forming a deposited film on the article.
In addition, the doping of an article using a microwave plasma doping apparatus is carried out, for example, as follows. A doping gas is introduced into a plasma generation chamber of the microwave plasma doping apparatus, and a microwave energy is simultaneously introduced therein to excite and decompose the doping gas, thereby doping a surface of the article.
With the microwave plasma processing apparatus, since microwaves of a high frequency are used as a gas excitation source, the number of electron accelerations is increased to increase the electron density, thereby efficiently ionizing and exciting gas molecules. Thus, the microwave plasma processing apparatus is advantageous in that the efficiency of ionization, excitation, and decomposition of a gas are high, so that it is possible to carry out fast, high quality processing even at a low temperature. In addition, there is a further advantage that the microwaves have a property of penetrating a dielectric, so that the plasma processing apparatus can be constituted as an electrodeless discharge type one, whereby highly clean plasma processing can be carried out.
As an example of a microwave plasma processing apparatus, there has recently been proposed an apparatus that uses an endless circular (or annular) waveguide having a plurality of linear slots radially formed in a planar H-place, as an apparatus for uniformly introducing microwaves efficiently (Japanese Patent Application Laid-Open No. 10-233295).
This microwave plasma processing apparatus is shown in FIG.
17
. In the figure, reference numeral
9
designates a plasma generation chamber; W an article;
2
a support means for the article W;
11
a means for adjusting the temperature of the article;
122
a high frequency bias applying means;
7
a processing gas introducing means;
8
an evacuation means;
4
a dielectric window for separating the plasma generation chamber
9
from the atmosphere;
3
a microwave applicator with slots
23
for introducing microwaves through the dielectric window
4
into the plasma generation chamber
9
;
13
an endless circular (or annular) waveguide; and
25
is an introducing port for introducing microwaves into the endless circular waveguide
13
to distribute them in the clockwise and the counterclockwise directions.
The generation of a plasma and the processing are carried out as follows. The inside of the plasma generation chamber
9
is evacuated via the evacuation means
8
. Subsequently, a plasma processing gas is introduced at a predetermined flow rate into the plasma generation chamber
9
via the processing gas introducing means
7
. Then, the inside of the plasma generation chamber
9
is kept at a predetermined pressure. If necessary, a bias voltage is applied to the article W with the high frequency bias applying means
122
. A desired power from a microwave power source is supplied into the plasma generation chamber
9
through the endless circular waveguide
13
. At this time, microwaves introduced into the endless circular waveguide
13
are distributed into two at the introducing port
25
and propagate within the waveguide
13
at a guide wavelength longer than the wavelength in the free space. The distributed microwaves interfere with each other to generate standing waves having a node or loop at every ½ of the guide wavelength. Microwaves introduced into the plasma generation chamber
9
through the dielectric window
4
from the slots
23
provided at such positions as to maximize the electric field, i.e., at the center of the endless circular waveguide
13
between adjoining two loops of standing waves generate a plasma in the vicinity of the slots
23
. When the electron plasma frequency of the generated plasma exceeds the power source frequency (for example, when the electron plasma frequency exceeds the power source frequency of 2.45 GHz in the case where the electron density exceeds 7×10
10
cm
−3
), the so-called cut-off in which microwaves cannot propagate through the plasma is caused. Further, when the electron density increases and the depth of penetration &dgr; defined by the following equation 1 becomes sufficiently small, microwaves propagate in a surface of the dielectric window
4
.
&dgr;=(2/&ohgr;&mgr;
o
&sgr;)
½
(Equation 1)
In the equation, &ohgr; is the angular frequency of a power source, &mgr;
o
is the space permeability, and &sgr; is the plasma conductivity (for example, when the electron density is 2×10
12
cm
−3
or more, and when the depth of penetration is 3 mm or less, microwaves propagate as surface waves in a surface of the dielectric window
4
). Surface waves introduced via adjoining slots
23
interfere with each other to generate surface standing waves whose loops are at every half wavelength of surface waves approximately defined by the following equation 2.
&lgr;
s
=&lgr;
o
/∈
r
−½
(Equation 2)
In the equation, &lgr;
o
is the free-space microwave wavelength, and ∈
r
is the dielectric constant of the dielectric window. The surface standing waves leaked to the plasma generation chamber
9
accelerate electrons, thus generating a surface-wave interfered plasma (SIP). At this time, when a processing gas is introduced into the plasma generation chamber
9
, the processing gas is excited by the thus generated high density plasma to process a surface of the article W placed on the support means
2
.
The use of such a microwave plasma processing apparatus can generate a high density, low electron temperature plasma of a uniformity within ±3%, an electron density 2×10
12
cm
−3
or more, an electron temperature 3 eV or less, and a plasma potential 15 V or less in a space with a large aperture of a diameter of 300 mm or more under the conditions of a pressure of 1.3 Pa and a microwave power of 3 kW. Thus, since the gas can fully be reacted and supplied in an active state to the article, and since article surface damage due to incident ions or charge-up can be reduced, high quality, high speed processing can be attained.
Further, under a high pressure condition of about 133 Pa such as adopted in the ashing or the like,
Suzuki Nobumasa
Yokoshima Shigenobu
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hassanzadeh Parviz
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