Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
2000-12-07
2003-10-28
Hassanzadeh, Parviz (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C156S345330, C118S7230MW
Reexamination Certificate
active
06638392
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to plasma process apparatuses, particularly to a plasma process apparatus such as an etching apparatus, CVD (Chemical Vapor Deposition) apparatus and ashing apparatus used in the fabrication process of semiconductors, liquid crystal display elements, solar cells, and the like.
2. Description of the Background Art
FIG. 6
is a schematic sectional view of a conventional plasma process apparatus formed as, for example, an ashing apparatus. Referring to
FIG. 6
, this plasma process apparatus includes an upper lid
101
, a chamber unit
102
, a substrate holder
107
, a dielectric-covered channel
113
, and a shield plate
114
.
Upper lid
101
is formed of a dielectric such as alumina, arranged on chamber unit
102
. A gasket (not shown) is provided between upper lid
101
and chamber unit
102
for sealing thereof, whereby process chamber
112
is isolated from the atmosphere. Process chamber
112
is maintained in vacuum by using a vacuum pump or the like in advance.
Substrate holder
107
to hold a substrate
108
is provided in process chamber
112
. The surface of substrate
108
placed on substrate holder
107
faces upper lid
101
. A gas introduction tube
111
is provided at the wall of chamber unit
102
. Raw material gas is supplied into process chamber
112
through gas introduction tube
111
.
Dielectric-covered channel
113
is provided above upper lid
101
. The top and outer perimeter of dielectric-covered channel
113
is surrounded by shield plate
114
. A microwave guide (not shown) is connected to dielectric-covered channel
113
.
In the ashing process using this conventional plasma process apparatus, predetermined material gas is supplied through gas introduction tube
111
into process chamber
112
. Microwave is introduced into process chamber
112
from upper lid
101
through dielectric-covered channel
113
. Plasma is exited in process chamber
112
, whereby the resist at the surface of substrate
108
is subjected to ashing.
In the aforementioned conventional plasma process apparatus, raw material gas is introduced from only one gas introduction tube
111
. Distribution of the raw material gas supplied into process chamber
112
is generated. Therefore, it was difficult to effect an ashing process uniformly.
The technique to solve this problem is disclosed in, for example, Japanese Patent No. 2669168 and Japanese Patent Laying-Open No. 7-335633.
FIG. 7
is a schematic sectional view of the plasma process apparatus disclosed in Japanese Patent No. 2669168. Referring to
FIG. 7
, this plasma process apparatus differs in structure from the plasma process apparatus of
FIG. 6
in that a showerhead
115
is provided and a plurality of gas introduction tubes
111
are connected symmetrically.
Showerhead
115
is located above substrate holder
107
and in the proximity of the bottom plane of upper lid
101
so as to cover the entire area of substrate
108
. Showerhead
115
includes a plurality of holes
115
a
. The outer peripheral portion of showerhead
115
is L-shaped in cross section. A buffer chamber
115
b
is formed by this portion. The termination end of showerhead
115
is fixedly connected to the inner wall of chamber unit
102
.
The remaining structure is similar to that of FIG.
6
. The same components have the same reference characters allotted, and description thereof will not be repeated.
In the operation of this apparatus, substrate
108
is placed on substrate holder
107
, followed by setting the interior of process chamber
112
to a predetermined level of vacuum. Then, predetermined gas is admitted into buffer chamber
115
b
through a plurality of gas introduction tubes
111
. The gas is introduced into process chamber
112
via hole
115
a
of showerhead
115
from buffer chamber
115
b
. Then, the microwave from a microwave guide is introduced into process chamber
112
from upper lid
101
through dielectric-covered channel
113
. Accordingly, plasma is generated by microwave excitation in process chamber
112
, whereby the resist at the surface of substrate
108
is subjected to ashing.
FIG. 8
is a schematic sectional view of a plasma process apparatus disclosed in Japanese Patent Laying-Open No. 7-335633. Referring to
FIG. 8
, this plasma process apparatus differs in structure from that of
FIG. 6
in the addition of a metal plate
116
.
Metal plate
116
is arranged in contact with the bottom plane of upper lid
101
. As shown in
FIG. 9
, metal plate
116
includes a microwave passage opening
116
c
in the form of a slit, a plurality of holes
116
a
formed at the substrate holder side plane, and a gas supply opening
116
d
provided at the side plane. Gas introduction tube
111
is connected to gas supply opening
116
d
. Metal plate
116
is hollow, so that gas supply opening
116
d
communicates with plurality of holes
116
a
inside. Upon supply of reaction gas from gas supply opening
116
d
, the reaction gas is blown out into process chamber
112
through the plurality of holes
116
a.
The remaining structure is similar to that of the plasma process apparatus of FIG.
6
. The same components have the same reference characters allotted, and description thereof will not be repeated.
In the operation of this apparatus, the interior of process chamber
112
is set to a predetermined level of vacuum after substrate
108
is placed on substrate holder
107
. Then, predetermined gas is introduced from gas introduction tube
111
into metal plate
116
through gas supply opening
116
d.
Gas blows out from the plurality of holes
116
a
of metal plate
116
to enter process chamber
112
. Microwave is introduced into process chamber
112
from a microwave passage opening
116
c
of metal plate
116
through dielectric-covered channel
113
and upper lid
101
. Accordingly, plasma is generated in process chamber
112
, whereby the resist at the surface of substrate
108
is subjected to ashing.
Recently, increase in the size of substrates is notable in the field of IC (Integrated Circuit) and liquid crystal. Particularly in the case of a TFT (Thin Film Transistor) liquid crystal display, the size of the substrate is as large as 500 mm square to 1 m square, or more. When these large substrates are to be subjected to a plasma process in apparatuses disclosed in Japanese Patent No. 2669168 and Japanese Patent Laying-Open No. 7-335633, problems set forth in the following are encountered.
In accordance with a larger substrate
108
, dielectric-covered channel
113
, upper lid
101
, showerhead
115
or metal plate
116
must also be increased in size so that the entirety of the large substrate
108
is covered. However, it is difficult to produce a large upper lid
101
since upper lid
101
is formed of a dielectric such as ceramics. Also, the cost will be increased. Furthermore, since upper lid
101
functions as a partition wall from the atmosphere, the thickness of upper lid
101
must be increased corresponding to the larger area in order to withstand the atmosphere while maintaining the interior of process chamber
112
in vacuum. However, it is difficult to form an upper lid
101
of a large size. The same applies for dielectric-covered channel
113
.
In the case where showerhead
115
of Japanese Patent No. 2669168 is formed of metal, the attachment of the reaction by-product on showerhead
115
will alter the plasma discharge characteristic. Also, since showerhead
115
is exposed to plasma, showerhead
115
will be increased in temperature by the heat generated from the plasma to cause thermal expansion. If showerhead
115
is formed of ceramic alone to avoid this problem, the size for process will be limited. Also, the cost of showerhead
115
will increase.
A larger substrate
108
also induces the problem that generation of uniform plasma becomes difficult. This is because the flow (conductance) of the reaction gas at gas introduction hole
115
a
differs between the outer circumferential side and inner circumferential side of showerhead
Hirayama Masaki
Ohmi Tadahiro
Tadera Takamitsu
Yamamoto Naoko
Yamamoto Tatsushi
Hassanzadeh Parviz
Sharp Kabushiki Kaisha
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