Coating processes – Coating by vapor – gas – or smoke
Reexamination Certificate
2000-09-22
2003-02-25
Lund, Jeffrie R. (Department: 1763)
Coating processes
Coating by vapor, gas, or smoke
C427S255230, C432S002000, C432S006000, C432S009000, C432S019000, C432S025000, C216S002000, C216S058000, C134S001300
Reexamination Certificate
active
06524650
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a substrate processing apparatus and method for performing predetermined processing on a substrate by utilizing a chemical reaction in the inside of a reaction enclosure. Incidentally, for example, an enclosure of double structure is used as the reaction enclosure. Further, for instance, CVD (Chemical Vapor Deposition) processing is adopted as the predetermined processing. Furthermore, for example, a thermal CVD processing or a plasma CVD processing is employed as this CVD processing.
2. Description of the Related Art
Generally, a film deposition apparatus for forming a predetermined thin film on a surface of a wafer is needed for producing a semiconductor device.
Example of this film deposition apparatus is CVD apparatus for performing film deposition by utilizing a chemical reaction in a hermetically enclosed reaction space.
Further, an example of such a CVD apparatus is a batch type CVD apparatus for forming predetermined thin films on a plurality of wafers at a time.
Furthermore, an example of such a batch type CVD apparatus is a vertical CVD apparatus wherein the plurality of wafers, on each of which thin film should be formed, are placed by being arranged vertically so that the horizontal sections of the wafers overlap with one another.
In the case of this vertical CVD apparatus, for instance, a reaction furnace of double structure, which has an outer tube and an inner tube, is used as the reaction enclosure.
In the vertical CVD apparatus using a reaction furnace of double structure as the reaction enclosure, a carrying-in/carrying-out opening is usually provided in the bottom end portion of the reaction furnace. Further, in this CVD apparatus, reaction gas for film deposition is usually supplied from the bottom end portion of the reaction furnace. Moreover, atmosphere contained in the inside of the reaction furnace is evacuated from the top end portion thereof through a space provided between the outer tube and the inner tube.
FIG. 13
is a side sectional diagram showing the configuration of the conventional vertical CVD apparatus which has the aforementioned reaction furnace of double structure. Hereinafter, the configuration of this conventional vertical CVD apparatus will be described. Incidentally, in the following description, this vertical CVD apparatus will be described as a low pressure CVD apparatus.
Vertical CVD apparatus
100
shown in this figure has: a reaction system
110
for forming a predetermined thin film on a wafer W by utilizing a chemical reaction in the inside (reaction space) of a reaction chamber
1
a;
a carrier system
120
for carrying the wafer W into the reaction chamber
1
a
and for carrying the wafer W therefrom; a gas supply system
130
of supplying into the reaction chamber a reaction gas for a film deposition process, an inert gas for performing what is called an after-purging process, and an inert gas for performing what is called an atmosphere restoring process; and an exhaust system
140
for the vacuum exhaust process (namely, the vacuum pumping process) of the reaction chamber
1
a.
Incidentally, the after-purging process is defined herein as a process consisting of the steps of supplying an inert gas into the reaction chamber
1
a,
and performing the vacuum-pumping of the reaction chamber
1
a
upon completion of the film deposition process, thereby purging the atmosphere away from the reaction chamber
1
a
by using the inert gas. Moreover, atmosphere restoring process is defined herein as a process consisting of the steps of stopping the vacuum exhaust process upon completion of the after-purging process, and then supplying an inert gas to the reaction chamber
1
a,
thereby restoring the inner pressure of the reaction chamber
1
a
to atmospheric pressure. This atmosphere restoring process is a process for preparing the apparatus for discharging the wafer W from the inside of the reaction chamber
1
a.
The reaction system
110
has a reaction furnace
111
for forming the reaction chamber
1
a.
This reaction furnace
111
is configured as a reaction furnace of double structure that has an outer tube
1
M and an inner tube
2
M. Throat
2
a,
through which a wafer W is carried in or out, is provided in the bottom end portion of this reaction furnace
111
.
Gas supply system
130
has a gas supply nozzle
131
that is used to supply a reaction gas for the film deposition process, an inert gas for the after-purging process, and another inert gas for the ambient gas restoring process. Gas blowoff opening
4
a
of this gas supply nozzle
131
is provided in the neighborhood of the throat
2
a
of the furnace
111
.
Exhaust system
140
has a main exhaust line
141
for performing a primary exhaust operation, an over-pressurization preventing line
142
for performing an over-pressurization preventing operation, and a bypass line
143
for performing a slow exhaust operation.
Incidentally, the primary exhaust operation is herein defined as an operation of performing a vacuum exhaust process on the reaction chamber
1
a
at high speed by increasing the exhaust conductance thereof. Further, the over-pressurization preventing operation is a vacuum exhaust process preventing the inner pressure of the reaction chamber
1
a
from exceeding atmospheric pressure in the atmosphere restoring process upon completion of the after-purging process. Moreover, the slow exhaust operation is herein defined as an operation of performing the vacuum exhaust process of the reaction chamber
1
a
at low speed by decreasing the exhaust conductance thereof.
Atmosphere exhaust port
5
a
of the exhaust system
140
is provided at a place where an atmosphere contained in the inside of the reaction chamber
1
a
is exhausted from the bottom end portion thereof through the space
3
a
between the outer tube
1
M and the inner tube
2
M.
In the case of the apparatus of the aforementioned configuration, when performing the film deposition process, first, a wafer W to be used therefor is carried into the reaction chamber
1
a
by the carrier system
120
. Upon completion of this carrying- into operation, a slow exhaust operation is performed on the reaction chamber
1
a
by a bypass line
143
. In this case, the atmosphere in the reaction chamber
1
a
is discharged from top end portion of the reaction furnace
111
through a space
3
a
between the outer tube
1
M and the inner tube
2
M.
When the degree of vacuum reaches a predetermined value as a result of a vacuum pumping process, a reaction gas for the film deposition is supplied by the gas supply system
130
to the vicinity of the throat
2
a.
Further, a primary exhaust operation is performed on the reaction chamber
1
a
by using a primary exhaust line
141
. Thus, the reaction gas flows from the bottom portion (namely, a gas supply side) of the reaction furnace
111
to the top portion (namely, an exhaust side) and is dispersed into the reaction chamber
1
a.
As a consequence, predetermined thin film is formed on the surface of the wafer W. Moreover, an unreacted gas (namely, a part of the reaction gas, which does not react chemically) and the vapor of a reaction by-product are discharged from the top portion of the reaction furnace
111
through the space
3
a.
When predetermined thin film is deposited on the surface of the wafer W, an inert gas is supplied by the gas supply system
130
to the reaction chamber
1
a.
At that time, the primary exhaust operation having been performed by the line
141
is continued without interruption. Consequently, the atmosphere in the reaction chamber
1
a
is purged by the inert gas. Upon completion of this after-purging process, the primary exhaust operation is terminated. Thus, only the operation of supplying the inert gas is continued. Thereby, the internal pressure of the reaction chamber
1
a
is increased.
When the internal pressure of the reaction chamber
1
a
exceeds atmospheric pressure, a vacuum exhaust process is performed on the reaction chamber
1
a
Maeda Kiyohiko
Nakamura Naoto
Sakamoto Ichiro
Shimahara Takashi
Kokusai Electric Co. Ltd.
Lund Jeffrie R.
Oliff & Berridg,e PLC
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