Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
2002-08-02
2004-04-27
Hassanzadeh, Parviz (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C118S7230MW, C315S111210
Reexamination Certificate
active
06726802
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma processing apparatus used in manufacturing semiconductor devices or liquid crystal displays, the plasma processing apparatus being employed as an apparatus for etching or depositing films by means of a plasma generated through excitation by microwave.
2. Description of the Background Art
A plasma processing technique which uses the microwave is applied to a process of manufacturing a semiconductor or TFT (Thin Film Transistor) liquid crystal substrate. This plasma processing technique is now in wide use because of a high plasma density as well as easy control of ion energy.
It is generally difficult, however, to uniformly generate the plasma over a large area. In addition, with recent increase in demand for semiconductor and TFT liquid crystal substrates as well as increased size of process substrates, a demand for a higher production efficiency and a demand for technique of uniform plasma-processing for a large-sized substrate are growing.
In order to satisfy such demands, some plasma processing apparatuses use a slot plate. A plasma processing apparatus using a slot plate is described below in conjunction with FIG.
10
.
FIG. 10
shows a structure of a conventional plasma processing apparatus employing a slot plate, the structure being shown in a cross section in the direction of the shorter side of a waveguide. Referring to
FIG. 10
, a chamber body
102
has a top chamber lid
101
placed via an O ring
109
to seal a process chamber
106
and keep a vacuum within process chamber
106
. A substrate holder
107
on which a substrate to be processed (hereinafter substrate)
108
is placed is provided in process chamber
106
. Further, a rectangular microwave entrance window
111
made of such a dielectric as alumina is formed in top chamber lid
101
via an O ring
110
.
Onto the vacuum side of top chamber lid
101
, a dielectric plate
115
is fastened by a dielectric plate fastening member
116
. Microwave entrance window
111
and dielectric plate
115
are fastened to contact each other. A vacuum is created in process chamber
106
by removing air from an opening
102
a
in the bottom of chamber body
102
by means of a vacuum pump (not shown). Chamber body
102
further has a gas inlet
105
provided for taking in a reactant gas.
A waveguide
103
is placed on top chamber lid
101
. A microwave generator (not shown) is connected to waveguide
103
. A metal slot plate
104
having a plurality of slots
104
a
is provided between microwave entrance window
111
and waveguide
103
.
Referring to
FIG. 11
, rectangular slots
104
a
are formed in a region corresponding in position to an opening of waveguide
103
. Slots
104
a
are accordingly placed between the waveguide opening
103
a
and microwave entrance window
111
. Slots
104
a
are positioned and sized appropriately so that a uniform plasma process is achieved under a certain process condition.
When this conventional plasma processing apparatus is operated, microwave is generated by the microwave generator (not shown), supplied through waveguide
103
, slots
104
a
of slot plate
104
and microwave entrance window
111
, and radiated from dielectric plate
115
into process chamber
106
, in order to change a reactant gas supplied from gas inlet
105
into a plasma. The plasma thus excited is used to plasma-process substrate
108
. As the slots
104
a
are positioned and sized most appropriately, substrate
108
is uniformly processed by the plasma.
In recent years, such multilayer films as two-layer and three-layer films have been used each as a material of a liquid crystal or semiconductor device. In addition, respective areas of liquid crystal substrates and semiconductor wafers have been increasing. Accordingly, a large-area workpiece formed of various types of films is often processed uniformly by a plasma successively in the same process chamber. Problems of such a process are described below in connection with a dry etching process.
Suppose that films made of different materials are to be etched or films made of the same material require different etching performances (e.g. shape, selectivity). Then, a process gas, an etching mode and an etching apparatus appropriate for each film must be selected, resulting in decrease of versatility of the apparatus.
Suppose that a film constituted of stacked layers of different materials is to be etched. If an apparatus and a condition that are most suitable for any layer of a certain material are selected in terms of the best uniformity, the best uniformity could not be achieved for other layers of materials different from that certain material. Consequently, a favorable uniformity cannot be achieved for the entire stacked-layer film.
Moreover, when isotropic etching and anisotropic etching are combined for etching a material into a desired shape, different process conditions, process gases for example, are necessary. In such a case, under significantly different conditions, it is difficult for a microwave plasma source to allow various materials on a large-area substrate or wafer to be etched into desired shapes by using one slot pattern.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a plasma processing apparatus keeping the uniformity in a plasma process under significantly different process conditions, for example, when films of different materials on a large-area substrate or wafer are to be processed or a film composed of stacked layers of different materials is to be processed.
According to the present invention, a plasma processing apparatus includes a process chamber, a microwave generating unit, a waveguide, a slot plate and a slot plate drive unit. The process chamber has a wall partially formed of a microwave entrance window made of a dielectric, for performing a plasma process in the process chamber. The microwave generating unit generates microwave. The waveguide supplies the microwave generated by the microwave generating unit into the process chamber via the microwave entrance window. The slot plate has a slot-formed region for passing the microwave from the waveguide to the microwave entrance window. The slot plate drive unit drives the slot plate to change the position of the slot plate with respect to the microwave entrance window. The slot-formed region has openings through which the microwave is passed, and the slot plate is moved with respect to the microwave entrance window to change at least one of the position, number and area of the openings of the slot-formed region.
The plasma processing apparatus of the present invention has the slot plate moved with respect to the microwave entrance window so that at least one of the position, number and area of the openings, which pass the microwave therethrough, of the slot-formed region of the slot plate can be changed. Then, for each process, the most appropriate state of the slot openings is provided. The process is thus carried out uniformly with stability.
With regard to the plasma processing apparatus, preferably the slot-formed region has a plurality of slots formed per the microwave entrance window and arranged in the direction in which the slot plate is moved, and the slot plate is moved to select, from those slots, slots passing the microwave and slots passing no microwave.
Accordingly, the most appropriate slots can be selected from a plurality of slots for each process so that the process can be carried out under the optimum condition.
With regard to the plasma processing apparatus, preferably the microwave entrance window has an open face in the shape of a rectangle on the wall of the process chamber, the slot plate is movable in the direction of the shorter side of the rectangle and, from those slots arranged in the direction of the shorter side, slots passing the microwave and slots passing no microwave are selected.
The slot plate is thus moved in the direction of the shorter side of the open face to select appropriate slots, which means that the distance of movemen
Hirayama Masaki
Ohmi Tadahiro
Tadera Takamitsu
Yamamoto Tatsushi
Conlin David G.
Edwards & Angell LLP
Hassanzadeh Parviz
Sharp Kabushiki Kaisha
Tucker David A.
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