Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With radio frequency antenna or inductive coil gas...
Reexamination Certificate
2002-07-30
2004-12-14
Alejandro-Mulero, Luz (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With radio frequency antenna or inductive coil gas...
C118S7230AN
Reexamination Certificate
active
06830653
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing method and apparatus to be used for manufacture of semiconductor or other electron devices and micromachines.
In the manufacture of semiconductor or other electron devices and micromachines, thin-film processing techniques using plasma processing have been becoming increasingly important in recent years.
As an example of conventional plasma processing methods, plasma processing using a patch-antenna type plasma source is described below with reference to FIG.
5
. Referring to
FIG. 5
, while interior of a vacuum chamber
1
is maintained to a specified pressure by introducing a specified gas from a gas supply unit
2
into the vacuum chamber
1
and simultaneously performing exhaustion by a turbo-molecular pump
3
as an exhauster, a high-frequency power of 100 MHz is supplied by an antenna use high-frequency power supply
4
to an antenna
5
provided so as to project into the vacuum chamber
1
. Then, plasma is generated in the vacuum chamber
1
, allowing plasma processing to be carried out with a substrate
7
placed on a substrate electrode
6
. There is also provided a substrate-electrode use high-frequency power supply
8
for supplying high-frequency power to the substrate electrode
6
, making it possible to control ion energy that reaches the substrate
7
. The high-frequency voltage supplied to the antenna
5
is delivered to a proximity to the center of the antenna
5
by a feed bar
9
. A plurality of sites of the antenna
5
other than its center and peripheries, and a face
27
of the vacuum chamber
1
opposite to the substrate
7
are short-circuited by short pins
10
. A dielectric plate
11
is sandwiched between the antenna
5
and the vacuum chamber
1
, and the feed bar
9
and the short pins
10
serve to connect the antenna
5
and the antenna use high-frequency power supply
4
to each other, and the antenna
5
and the vacuum chamber
1
to each other via through holes provided in the dielectric plate
11
. Also, surfaces of the antenna
5
are covered with an antenna cover
15
. The antenna cover
15
is fixed to the antenna
5
by bolts
25
. Further, a slit
14
is provided so as to comprise a recessed or grooved space between the dielectric plate
11
and a dielectric ring
12
provided at a peripheral portion of the dielectric plate
11
, and a recessed or grooved space between the antenna
5
and a conductor ring
13
provided at a peripheral portion of the antenna
5
.
The turbo-molecular pump
3
and an exhaust port
19
are disposed just under the substrate electrode
6
, and a pressure-regulating valve
20
for controlling the vacuum chamber
1
to a specified pressure is an up-and-down valve disposed just under the substrate electrode
6
and just over the turbo-molecular pump
3
. The substrate electrode
6
is fixed to the vacuum chamber
1
with four pillars
21
.
In the plasma processing described in the above prior-art example, however, plasma density would become the highest at the slit, posing an issue of damage of a bottom face
26
of the slit. The vacuum chamber, which is typically made of aluminium, is generally coated with anodic oxide (alumite) for prevention of corrosion of the inner wall surface of the vacuum chamber. However, the alumite of the slit bottom face would be damaged and, over repeated plasma processing, the alumite would become gradually thinner and thinner. According to our experiments, when the thickness of alumite was measured before and after an about 1,000 pcs. etching process, an about 10 &mgr;m decrease of film thickness was found. Shortage of the alumite thickness would lead to problems such as corrosion of base-material aluminium or occurrence of dust. For prevention of this, it is necessary to disassemble most of the plasma source unit and replace the aluminium member, which is heavy and expensive, unfortunately. Furthermore, since the antenna cover
15
is fixed to the antenna
5
by the bolts
25
, deposited film resulting from the plasma processing tends to be peeled off from the vicinities of the bolts
25
, causing occurrence of dust, as another problem.
Meanwhile, in the plasma processing described in the prior-art example, there is an issue that the temperature of the antenna cover
15
increases due to plasma exposure. Since the antenna cover
15
and the antenna
5
are vacuum-insulated from each other, the temperature of the antenna cover
15
gradually increases over repeated plasma processing. According to our experiments, it was found that the temperature of the antenna cover
15
increases up to 170° C. after 5-min. plasma processing and 1-min. vacuum holding is repeated six times. Such an abrupt change in the temperature of the antenna cover
15
may cause not only occurrence of dust but also cracks of the antenna cover
15
.
In view of these and other prior-art issues, an object of the present invention is to provide a plasma processing method and apparatus which is less liable to occurrence of dust and cracks of the antenna cover.
SUMMARY OF THE INVENTION
In accomplishing these and other aspects, according to a first aspect of the present invention, there is provided a plasma processing method for generating plasma in a vacuum chamber and processing a substrate placed on a substrate electrode, the plasma being generated by supplying a high-frequency power having a frequency of 50 MHz to 3 GHz to an antenna provided opposite to the substrate electrode while interior of the vacuum chamber is controlled to a specified pressure by supplying a gas into the vacuum chamber and exhausting the interior of the vacuum chamber,
the method comprising: with a dielectric plate being sandwiched between the antenna and the vacuum chamber and both the antenna and the dielectric plate projecting into the vacuum chamber,
controlling plasma distribution on the substrate with an annular and recessed slit provided between the antenna and the vacuum chamber; and
processing the substrate in a state where the antenna cover is fixed by making both an inner side face of the slit and the antenna covered with an antenna cover, making a bottom face of the slit covered with a slit cover, supporting the antenna cover by the slit cover, and fixing the slit cover to a wall surface of the vacuum chamber.
According to a second aspect of the present invention, there is provided a plasma processing method according to the first aspect, wherein the substrate is processed with the slit cover is a conductor and with electric conduction between the slit cover and the vacuum-chamber wall surface ensured by a spiral tube.
According to a third aspect of the present invention, there is provided a plasma processing method according to the first aspect, wherein the substrate is processed with the slit cover is an insulating member.
According to a fourth aspect of the present invention, there is provided a plasma processing method for generating plasma in a vacuum chamber and processing a substrate placed on a substrate electrode within the vacuum chamber, the plasma being generated by supplying a high-frequency power having a frequency of 50 MHz to 3 GHz to an antenna provided opposite to the substrate electrode while interior of the vacuum chamber is controlled to a specified pressure by supplying a gas into the vacuum chamber and exhausting the interior of the vacuum chamber,
the method comprising: with a dielectric plate being sandwiched between the antenna and the vacuum chamber and both the antenna and the dielectric plate projecting into the vacuum chamber,
controlling plasma distribution on the substrate by an annular and recessed slit provided between the antenna and the vacuum chamber; and
processing the substrate while controlling temperature of the antenna by making both an inner side face of the slit and the antenna covered with an antenna cover and applying a refrigerant flow to the antenna while ensuring heat conduction between the antenna and the antenna cover by a heat-conducting sheet provided between the antenna and the antenna cover.
Kai Takayuki
Maegawa Yukihiro
Matsuda Izuru
Okumura Tomohiro
Saitoh Mitsuo
Alejandro-Mulero Luz
Matsushita Electric - Industrial Co., Ltd.
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