Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With radio frequency antenna or inductive coil gas...
Reexamination Certificate
2000-07-06
2002-11-05
Goudreau, George (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With radio frequency antenna or inductive coil gas...
C156S345440, C156S345380, C156S345100, C216S068000, C118S7230IR, C118S7230IR
Reexamination Certificate
active
06475334
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dry etching device and dry etching method, and particularly to an inductively coupled plasma dry etching device and dry etching method.
2. Description of the Related Art
In processing wafers in a semiconductor fabrication process, a dry etching process is carried out in which etching is performed using active gas plasma under reduced pressure to remove only a prescribed thickness of a prescribed area of a thin film formed on a wafer, one type of dry etching device that is used being an inductively coupled plasma (ICP) dry etching device. An inductively coupled plasma dry etching device is a plasma etching device that uses a plasma created by accelerating electrons in an induction field that is brought about by a high-frequency induced magnetic field. The shape of the inductively coupled plasma may be a spiral coil or a coil on flat plate.
FIG. 1A
is an overall schematic sectional view of an inductively coupled plasma dry etching device of the prior art, and
FIG. 1B
is a sectional view of the dome. An inductively coupled plasma dry etching device of the prior art includes etching chamber
110
that houses wafer
130
that is to undergo the etching process, and ceramic dome
120
that is connected to the opening of etching chamber
110
and that is provided for generating plasma within the device. Etching chamber
110
can be maintained in an airtight state while coupled with dome
120
.
Etching chamber
110
is provided with gate
111
for inserting and removing wafer
130
and gas injection port
112
for introducing the etching gas. In addition, ESC (electrostatic chuck) stage
131
made of ceramic for securing wafer
130
is provided inside etching chamber
110
, while outside etching chamber
110
, pressure gauge
113
and pressure controller
140
for regulating gas pressure inside the chamber and discharging gas are connected, and first high-frequency power supply
123
for supplying high-frequency current is connected to ESC stage
131
.
Coil
121
is arranged in a helical form on the outside of dome
120
, and coil
121
is connected to second high-frequency power supply
124
.
Next, regarding the etching method that uses the inductively coupled plasma dry etching device of the prior art, wafer
130
is conveyed by way of gate
111
of etching chamber
110
onto ceramic ESC stage
131
, which has the function of securing the wafer. Etching gas is directed at wafer
130
, which is secured on ceramic ESC stage
131
, from gas injection port
112
directly over wafer
130
. The pressure inside etching chamber
110
is detected by gauge
113
, and the interior of etching chamber
110
is controlled to a prescribed pressure by linking this detected pressure with an orifice of pressure controller
140
, which serves as an exhaust gas outlet, and varying the orifice.
High-frequency power of 13.56 MHz is applied from second high-frequency power supply
124
to coil
121
, which is arranged on the exterior surface of ceramic dome
120
, high-frequency power of 13.56 MHz is next applied from first high-frequency power supply
123
to ceramic ESC stage
131
, and the etching gas inside etching chamber
110
is excited to generate plasma. The excited plasma thereupon etches wafer
130
on ceramic ESC stage
131
.
During the etching process, the ceramic of dome
120
is etched at the points on the inside surface of ceramic dome
120
that correspond to coil
121
as shown in
FIG. 2B
, while conversely, deposition
126
adheres to the points that correspond to positions where coil
121
is not present.
After the etching process is completed, first high-frequency power supply
123
and second high-frequency power supply
124
are halted and the supply of etching gas is stopped. When the etching process has been completed, wafer
130
is removed by way of gate
111
of etching chamber
110
.
However, the above-described inductively coupled plasma dry etching device of the prior art has the following problems.
First, a reaction product adheres as deposition
126
to the points on the inside surface of ceramic dome
120
that correspond to positions where coil
121
is not present. If the wafer processing continues without addressing this issue, deposition
126
tends to peel off and produce particles on the wafer. As a result, not only must the interior of dome
120
be subjected to cleaning at short intervals, but particles tend to be generated, and the device availability rate drops.
Second, there is the problem that as etching of the interior surface of ceramic dome
120
progresses at points that correspond to coil
121
, ceramic dome
120
is reduced and the life of dome
120
is shortened.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a dry etching device and dry etching method that tend not to produce particles, and that feature a high device availability rate and a ceramic dome having longer life.
The dry etching device of the present invention is an inductively coupled plasma dry etching device in which etching is carried out by causing an active gas plasma to act on a wafer secured inside an etching chamber under reduced pressure; the dry etching device being provided with: an etching chamber, a plasma generation means, a wafer securing means, an etching gas supply means, and a gas pressure control means. The plasma generation means includes two high-frequency power supplies that can be switched, and two coils for high-frequency power application that are connected to the two high-frequency power supplies. The two coils for high-frequency power application are each arranged in proximity to the other such that turns of each coil lie between turns of the other coil.
The plasma generation means may have a dome, and the two coils for high-frequency power application may be arranged around the outside of the dome in a helical form such that turns of each coil lie between turns of the other coil; or the plasma generation means may have a quartz plate and the two coils for high-frequency power application may be arranged on the outer surface of the quartz plate in a spiral form such that turns of each coil lie between turns of the other coil.
The dry etching method of the present invention is a method for performing dry etching by causing active gas plasma to act on a wafer that is secured inside an etching chamber under reduced pressure. In a dry etching method that employs an inductively coupled plasma dry etching device, etching is carried out by: conveying a wafer into an etching chamber and securing the wafer, introducing an etching gas into the etching chamber, regulating the interior of the etching chamber to a prescribed pressure, supplying high-frequency power from high-frequency power supplies to either of two coils for high-frequency power application belonging to a plasma generation means that are arranged in proximity to each other such that turns of each coil lie between turns of the other coil, and activating the etching gas; and further, switching the two high-frequency power supplies at a prescribed time interval so as to alternately supply high-frequency power to one of the two coils for high-frequency power application that are each connected to a respective power supply.
The interval of switching the high-frequency power supplies may be 1
th of the time required for a prescribed etching process of one wafer, n being an even number; may be ½ the time required for a prescribed etching process of one wafer; or may be the time required for a prescribed etching process of one wafer, the high-frequency power supplies being switched with each exchange of a wafer.
The dry etching device of the present invention is an etching device that employs a plasma source which is an inductively coupled plasma method, includes two inductively coupled coils, and allows high-frequency power to be independently applied to each of the two coils.
High-frequency power is alternately applied to two coils that are arranged in helical or spiral form such that a
Goudreau George
McGinn & Gibb PLLC
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