U.S. patent application number 14/269360 was filed with the patent office on 2015-01-22 for efem and load port.
This patent application is currently assigned to SINFONIA TECHNOLOGY CO., LTD.. The applicant listed for this patent is SINFONIA TECHNOLOGY CO., LTD.. Invention is credited to Mitsuo Natsume, Mitsutoshi Ochiai, Atsushi Suzuki, Yasushi Taniyama.
Application Number | 20150024671 14/269360 |
Document ID | / |
Family ID | 52319604 |
Filed Date | 2015-01-22 |
United States Patent
Application |
20150024671 |
Kind Code |
A1 |
Taniyama; Yasushi ; et
al. |
January 22, 2015 |
EFEM AND LOAD PORT
Abstract
There is provided an EFEM that includes a shield gas curtain
apparatus 6 that forms a gas curtain capable of shielding an
opening 23 when an internal space 5S of a purge container 5, in
which the humidity is reduced to a predetermined value by means of
a bottom purge apparatus 25 provided in a load port 2, is brought
into communication with an internal space 3S of a wafer transport
chamber 3, the gas curtain being formed of a shield curtain gas
blown immediately downward from a location near the opening 23 of
the load port 2 and being closer to the wafer transport chamber 3
than the opening 23 at a higher height than an upper edge of the
opening 23. The EFEM thus configured can prevent and suppress a
rapid increase in the humidity in the purge container, in which the
humidity in the interior space is reduced by performing the bottom
purging, occurring immediately after a lid of the purge container
is opened, so that quality degradation due to the moisture adhered
on a wafer can be avoided.
Inventors: |
Taniyama; Yasushi; (Tokyo,
JP) ; Ochiai; Mitsutoshi; (Tokyo, JP) ;
Natsume; Mitsuo; (Tokyo, JP) ; Suzuki; Atsushi;
(Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SINFONIA TECHNOLOGY CO., LTD. |
Tokyo |
|
JP |
|
|
Assignee: |
SINFONIA TECHNOLOGY CO.,
LTD.
Tokyo
JP
|
Family ID: |
52319604 |
Appl. No.: |
14/269360 |
Filed: |
May 5, 2014 |
Current U.S.
Class: |
454/193 |
Current CPC
Class: |
H01L 21/67017 20130101;
H01L 21/67772 20130101; F24F 3/161 20130101; F24F 9/00
20130101 |
Class at
Publication: |
454/193 |
International
Class: |
F24F 9/00 20060101
F24F009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 16, 2013 |
JP |
2013-147207 |
Claims
1. An EFEM, comprising: a wafer transport chamber; a load port
adjacent to the wafer transport chamber; and a shield gas curtain
apparatus, wherein the load port includes a bottom purge apparatus
capable of replacing a gaseous atmosphere in a purge container with
a purge gas composed of nitrogen or dry air from the bottom side of
the purge container, and wherein the shield gas curtain apparatus
forms a gas curtain capable of shielding an opening of the load
port when an internal space of the purge container, in which at
least humidity is reduced to a predetermined value by supplying the
purge gas from the bottom purge apparatus, is brought into
communication with an internal space of the wafer transport chamber
through the opening, the gas curtain being formed of a shield
curtain gas composed of nitrogen or dry air blown immediately
downward or obliquely downward such that the gas diverges from the
purge container, from a location near the opening and being closer
to the wafer transport chamber than the opening at the same height
as or a higher height than an upper edge of the opening.
2. A load port adjacent to a wafer transport chamber, comprising: a
bottom purge apparatus; and a shield gas curtain apparatus, wherein
the bottom purge apparatus is capable of replacing a gaseous
atmosphere in a purge container with a purge gas composed of
nitrogen or dry air from the bottom side of the purge container,
and wherein the shield gas curtain apparatus forms a gas curtain
capable of shielding an opening when an internal space of the purge
container, in which at least humidity is reduced to a predetermined
value by supplying the purge gas from the bottom purge apparatus,
is brought into communication with an internal space of the wafer
transport chamber through the opening, the gas curtain being formed
of a shield curtain gas composed of nitrogen or dry air blown
immediately downward or obliquely downward such that the gas
diverges from the purge container, from a location near the opening
and being closer to the wafer transport chamber than the opening at
the same height as or a higher height than an upper edge of the
opening.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an EFEM composed of a wafer
transport chamber and a load port, and to a load port.
[0003] 2. Description of the Related Art
[0004] In a semiconductor manufacturing process, wafers are
processed in a clean room to improve yield and quality. Today,
however, when the trends of high integration of devices and circuit
miniaturization along with the adoption of larger wafers have
progressed, it has become difficult to manage small dusts in an
entire clean room in view of costs as well as from a technical
point of view. Accordingly, instead of increasing the cleanliness
of the entire interior of such a clean room, a system that
incorporates "mini-environment system," which locally increases the
cleanliness only around wafers, has been adopted recently for
transporting and otherwise processing wafers. The mini-environment
system includes a storage container known as a Front-Opening
Unified Pod (FOUP) for transporting and retaining a wafer in a
highly clean environment. Such a FOUP constitutes an Equipment
Front End Module (EFEM) in combination with a wafer transport
chamber. In addition, a load port is used as important equipment,
which functions as an interface for allowing a FOUP to exchange a
wafer with the wafer transport chamber and for passing/receiving a
FOUP itself to/from a FOUP transport apparatus.
[0005] The load port is provided with a door section, which is
brought into close contact with a lid provided in a front face of
the FOUP. The door section and the lid are opened at the same time
while in close contact with each other, and a wafer transport robot
such as an arm robot provided in the wafer transport chamber can
unload a wafer in the FOUP into the wafer transport chamber and
store a wafer in the FOUP through the load port from the wafer
transport chamber. A module consisting of the wafer transport
chamber, which provides a space including such a wafer transport
robot located therein, along with the load port is referred to as
an EFEM.
[0006] As miniaturization of semiconductor devices on a wafer or
the like progresses, there is growing concern about quality
degradation due not only to contamination but also to moisture
adhered on a wafer in these days, leading to a necessity of keeping
a clean and low humidity environment around wafers.
[0007] Accordingly, as a technique of injecting a predetermined gas
into a FOUP to replace the atmosphere in the FOUP with the
predetermined gas for providing a low humidity environment inside
the FOUP, Japanese Patent Laid-Open No. 2007-180516 discloses a
load port including a purge apparatus that opens a lid of a FOUP at
a door section of the load port and blows a predetermined gas
(e.g., nitrogen or inert gas) into the FOUP by a purge section
provided closer to the wafer transport chamber than the opening
while internal spaces of the FOUP and the wafer transport chamber
communicate with each other through the opening of the load
port.
[0008] Such a purge apparatus using a so-called front purge system,
which injects a predetermined gas from the front (the side facing
the door section of the load port) into a FOUP and replaces the
atmosphere in the FOUP with the predetermined gas, allows the
purging to be performed only while the lid of the FOUP is opened at
the door section of the load port.
[0009] Japanese Patent Laid-Open No. 2011-187539 discloses a load
port including a purge apparatus that injects a predetermined gas
(e.g., nitrogen or inert gas) into a FOUP loaded with wafers placed
on a table of the load port from the bottom to fill the FOUP and
replace the atmosphere in the FOUP with the predetermined gas. The
purge apparatus using a so-called bottom purge system, which
injects gas such as nitrogen or dry air from the bottom of a FOUP
into the FOUP and replaces the atmosphere in the FOUP with the
predetermined gas, has an advantage over a purge apparatus using a
front purge system that allows the purging to be performed only
while the lid of the FOUP is opened at the door section of the load
port in that the purging can be performed even while the lid of the
FOUP is not opened at the door section of the load port. In
addition, since the purging can be started upon receiving a FOUP at
the load port from a transport apparatus such as an OHT (Overhead
Hoist Transfer), the apparatus using a bottom purge system is
advantageous over the one using a front purge system in that a
higher maximum concentration of the predetermined gaseous
atmosphere can be reached.
[0010] Furthermore, immediately after a FOUP is received from a
transport apparatus such as an OHT at the load port, the bottom
purging can be performed to replace the atmosphere in the FOUP with
the predetermined gas, so that at least the humidity in the FOUP is
reduced to a predetermined value or lower to keep a low humidity
environment around wafers. In this way, quality degradation due to
the moisture adherence on a wafer can be prevented or
suppressed.
[0011] It has been found that when the lid of the FOUP is opened at
the door section of the load port while a low humidity environment
is maintained inside the FOUP, which is a purge container, once the
bottom purging is performed to replace the atmosphere in the FOUP
with the predetermined gas, the internal space of the FOUP is
brought into communication with that of the wafer transport chamber
through the opening of the load port, and the gaseous atmosphere in
the wafer transport chamber enters the internal space of the FOUP,
which may result in a rapid increase in the humidity in the
FOUP.
[0012] Such a rapid increase in the humidity in the FOUP, which has
once been reduced by the bottom purging down to a predetermined
value or lower in order to secure a low humidity environment, may
increase the possibility of moisture being adhered on a wafer and
lead to a potential degradation of quality. Accordingly, there
would be a need for a mechanism for reducing the humidity in the
FOUP as necessary. It has also been found that the oxygen
concentration in the FOUP shows the same trend as the humidity; if
the oxygen concentration in the FOUP increases when the lid of the
FOUP is opened, an oxide film may disadvantageously be formed on
the wafer. Accordingly, the oxygen concentration in the FOUP could
also be reduced by a mechanism for reducing the humidity in the
FOUP as necessary.
[0013] Japanese Patent Laid-Open No. 2007-180516 discloses a
technique of forming a gas curtain for closing the plane of the
opening by discharging an inert gas from a curtain nozzle arranged
on the upper portion of the opening at the same time as the front
purging. According to the technique, stated advantages are that a
gas entering a pod from outside the pod is suppressed by the gas
curtain and that the concentration of an inert gas in the pod is
maintained by supplying the inert gas into the pod. It is disclosed
that the advantages can be combined to continuously maintain a
partial pressure of an oxidizing gas in the pod at a predetermined
low pressure even while the pod is opened.
[0014] However, since the front purging disclosed in Japanese
Patent Laid-Open No. 2007-180516 can be performed only while the
lid of the FOUP is opened at the door section of the load port, it
has a disadvantage of a maximum concentration of gaseous atmosphere
being lower than that reachable by the bottom purging. Even though
such a relatively lower maximum concentration of gaseous atmosphere
can be maintained, a relatively higher maximum concentration of
gaseous atmosphere, as can be reached by the bottom purging, cannot
be maintained, so that it is not expected to completely eliminate
the possibility of moisture being adhered on a wafer in the gaseous
atmosphere in the FOUP, which leads to a potential degradation of
quality.
[0015] The present invention has been made in consideration of the
above-described problems, and a main object thereof is to provide
an EFEM and a load port, which adopt a bottom purge system capable
of purging leading to a high maximum concentration of a
predetermined gaseous atmosphere, while preventing and suppressing
a rapid increase in at least the humidity in a purge container
occurring immediately after a lid of the purge container is opened
and the internal space of the purge container is brought into
communication with that of a wafer transport chamber, so that
quality degradation due to the moisture adhered on a wafer can be
avoided.
SUMMARY OF THE INVENTION
[0016] The present invention relates to an EFEM including a wafer
transport chamber and a load port adjacent to the wafer transport
chamber. In the EFEM according to the present invention, the load
port includes a bottom purge apparatus capable of replacing a
gaseous atmosphere in a purge container with a purge gas composed
of nitrogen or dry air from the bottom side of the purge container.
The EFEM further includes a shield gas curtain apparatus that forms
a gas curtain capable of shielding an opening of the load port when
an internal space of the purge container, in which at least
humidity is reduced to a predetermined value by supplying the purge
gas from the bottom purge apparatus, is brought into communication
with an internal space of the wafer transport chamber through the
opening, the gas curtain being formed of a shield curtain gas
composed of nitrogen or dry air blown immediately downward or
obliquely downward such that the gas diverges from the purge
container, from a location near the opening and being closer to the
wafer transport chamber than the opening at the same height as or a
higher height than an upper edge of the opening.
[0017] The EFEM thus configured can perform purging leading to a
high maximum concentration of a predetermined gaseous atmosphere by
the bottom purge apparatus so as to maintain a low humidity at or
below a predetermined value in the purge container. Even when the
internal space of the purge container is in communication with that
of the wafer transport chamber, a gas curtain that shields the
opening of the load port can be formed by the shield gas curtain
apparatus to prevent and suppress the entrance of the gaseous
atmosphere in the wafer transport chamber into the purge container.
Consequently, even after the internal space of the purge container
is in communication with that of the wafer transport chamber, a low
humidity can be maintained in the purge container and a rapid
increase in the humidity in the purge container can be avoided.
According to the EFEM of the present invention, which is capable of
thus maintaining a low humidity in the purge container, adherence
of moisture onto a wafer in the purge container can be prevented
and suppressed, and quality degradation due to the moisture adhered
on a wafer can be avoided.
[0018] Even when a gas curtain is formed by the shield gas curtain
apparatus provided in the EFEM according to the present invention,
it is conceivable that the humidity in the purge container may
somewhat increase after the internal space of the purge container
is brought into communication with that of the wafer transport
chamber from the level at that time. The increased humidity,
however, will reach a peak at some point in time and the peak level
will be smaller than the case where a gas curtain is not formed by
the shield gas curtain apparatus, which is small enough to prevent
and suppress adherence of moisture onto a wafer. In view of this
point, according to the EFEM of the present invention, during a
process of bottom purging to reduce the humidity in the purge
container with the bottom purge apparatus while the internal space
of the purge container is not in communication with that of the
wafer transport chamber, wafer transportation can be started when
the humidity reaches the same level as the above-described peak
level by bringing the internal space of the purge container into
communication with that of the wafer transport chamber. In this
way, time needed from when bottom purging is started for the purge
container to when the internal space of the purge container is
brought into communication with that of the wafer transport chamber
can be reduced, leading to tact time reduction, and consequently,
an improved efficiency of wafer processing.
[0019] The present invention relates to a load port adjacent to the
wafer transport chamber, the load port including a bottom purge
apparatus and a shield gas curtain apparatus. The bottom purge
apparatus is capable of replacing a gaseous atmosphere in the purge
container with a purge gas composed of nitrogen or dry air from the
bottom side of the purge container. The shield gas curtain
apparatus is an apparatus that forms a gas curtain capable of
shielding an opening when the internal space of the purge
container, in which at least humidity is reduced to a predetermined
value by supplying the purge gas from the bottom purge apparatus,
is brought into communication with the internal space of the wafer
transport chamber through the opening, the gas curtain being formed
of a shield curtain gas composed of nitrogen or dry air blown
immediately downward or obliquely downward such that the gas
diverges from the purge container, from a location near the opening
and being closer to the wafer transport chamber than the opening at
the same height as or a higher height than an upper edge of the
opening.
[0020] The load port has advantages similar to the EFEM.
Specifically, it is possible to perform purging leading to a high
maximum concentration of a gaseous atmosphere by the bottom purge
apparatus so as to maintain a low humidity at or below a
predetermined value in the purge container. Even when the internal
space of the purge container is in communication with that of the
wafer transport chamber, a gas curtain that shields the opening can
be formed by the shield gas curtain apparatus to prevent and
suppress the entrance of the gaseous atmosphere in the wafer
transport chamber into the purge container. Consequently, even
after the internal space of the purge container is in communication
with that of the wafer transport chamber, a low humidity can be
maintained in the purge container and a rapid increase in the
humidity in the purge container can be avoided. According to the
load port of the present invention, which is capable of thus
maintaining a low humidity in the purge container, adherence of
moisture onto a wafer in the purge container can be prevented and
suppressed, and quality degradation due to the moisture adhered on
a wafer can be avoided.
[0021] Even when a gas curtain is formed by the shield gas curtain
apparatus provided in the load port according to the present
invention, it is conceivable that the humidity in the purge
container may somewhat increase after the internal space of the
purge container is brought into communication with that of the
wafer transport chamber from the level at that time. The increased
humidity, however, will reach a peak at some point in time and the
peak level will be smaller than the case where a gas curtain is not
formed by the shield gas curtain apparatus, which is small enough
to prevent and suppress adherence of moisture onto a wafer. In view
of this point, according to the load port of the present invention,
during a process of bottom purging to reduce the humidity in the
purge container with the bottom purge apparatus while the internal
space of the purge container is not in communication with that of
the wafer transport chamber, wafer transportation can be started
when the humidity reaches the same level as the above-described
peak level by bringing the internal space of the purge container
into communication with that of the wafer transport chamber. In
this way, time needed from when bottom purging is started for the
purge container to when the internal space of the purge container
is brought into communication with that of the wafer transport
chamber can be reduced, leading to tact time reduction, and
consequently, an improved efficiency of wafer processing.
[0022] Furthermore, according to the EFEM and the load port of the
present invention, a low oxygen concentration in the purge
container can also be maintained, the oxygen being a cause of wafer
oxidation.
[0023] Note that "purge container" of the present invention
includes containers in general that is portable with a wafer
contained therein and has a space to be purged therein, one example
of which includes a FOUP.
[0024] According to the present invention, an EFEM and a load port
can be provided, which include a bottom purge apparatus for bottom
purging and a shield gas curtain apparatus that forms a gas
curtain, and operate these apparatuses to prevent and suppress a
rapid increase in the humidity or the oxygen concentration in a
purge container occurring immediately after the internal space of
the purge container is brought into communication with that of a
wafer transport chamber, so that quality degradation due to the
moisture adhered on a wafer can be avoided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 schematically illustrates a relative positional
relation of an EFEM and peripheral apparatuses, and airflows in a
FOUP and a wafer transport chamber with the doors closed, according
to a first embodiment of the present invention;
[0026] FIG. 2 is a graphical representation illustrating a humidity
variation in the FOUP when a shield gas curtain apparatus is not
operated in the first embodiment;
[0027] FIG. 3 schematically illustrates airflows in the FOUP and
the wafer transport chamber with the doors opened in the first
embodiment;
[0028] FIG. 4 is a graphical representation illustrating a humidity
variation in the FOUP when the shield gas curtain apparatus is
operated in the first embodiment;
[0029] FIG. 5 is a graphical representation corresponding to FIG.
4, illustrating the fact that the door opening timing can be set
earlier in the first embodiment;
[0030] FIG. 6 schematically illustrates a relative positional
relation of a load port and peripheral apparatuses and airflows in
a FOUP and a wafer transport chamber with the doors closed,
according to a second embodiment of the present invention; and
[0031] FIG. 7 schematically illustrates airflows in the FOUP and
the wafer transport chamber with the doors opened in the second
embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] A first embodiment of the present invention will now be
described with reference to drawings.
[0033] As illustrated in FIG. 1, an EFEM 1 according to the
embodiment is composed of a load port 2 and a wafer transport
chamber 3 adjacent to each other in a common clean room. FIG. 1 is
a diagram of the load port 2 and its surroundings when viewed from
one side, and schematically illustrates a relative positional
relation of the load port 2 and the wafer transport chamber 3, as
well as a relative positional relation of the EFEM 1, which is
composed of the load port 2 and the wafer transport chamber 3, a
semiconductor manufacturing apparatus 4, and a FOUP 5, which is a
purge container.
[0034] The FOUP 5 illustrated by a long dashed double-short-dashed
line in FIG. 1 houses a plurality of wafers therein, is configured
to allow the wafers to be exchanged through a
carrying-in/carrying-out port 51 formed in a front face, and
includes a lid 52 capable of opening and closing the
carrying-in/carrying-out port 51. Such a FOUP is well known and
further description will be omitted. Note that the front face of
the FOUP 5 in the embodiment refers to a surface that faces a door
section 24 of the load port 2 when the FOUP 5 is placed on the load
port 2. A bottom 53 of the FOUP 5 has purge ports provided at
predetermined locations. Each port is mainly composed of, for
example, a hollow cylindrical grommet seal fit in a purge through
hole formed in the bottom 53 of the FOUP 5. A valve that switches
from a closed state to an opened state by the injection pressure or
discharge pressure of gas (to be described later) such as nitrogen,
inert gas, or dry air (note that nitrogen gas is used in the
embodiment and may be referred to as "purge gas" in the description
below) is provided in the grommet seal.
[0035] The semiconductor manufacturing apparatus 4 includes, for
example, a semiconductor manufacturing apparatus main body 41 that
is located relatively farther from the wafer transport chamber 3
and a load lock chamber 42 that is located relatively closer to the
wafer transport chamber 3. In the embodiment, the load port 2, the
wafer transport chamber 3, the load lock chamber 42, and the
semiconductor manufacturing apparatus main body 41 are arranged in
close contact with each other in this order.
[0036] The wafer transport chamber 3 is provided with a wafer
transport robot (not shown) capable of transporting a wafer between
the FOUP 5 and the semiconductor manufacturing apparatus in an
internal space 3S. The EFEM 1 of the embodiment is provided with a
fan filter unit (FFU) 33, which is composed of a fan 31 and a
filter 32 as a unit, in the upper portion (ceiling) of the wafer
transport chamber 3. The FFU 33 blows clean air (dry air)
continuously or as necessary while the EFEM 1 is in operation, and
guides the air to flow downward from the top in the wafer transport
chamber interior 3S so as to maintain a high cleanliness in the
wafer transport chamber interior 3S.
[0037] The load port 2 is used to open and close a lid 52 of the
FOUP 5 in a close contact state and allow a wafer to be exchanged
between the FOUP interior 5S and the wafer transport chamber
interior 3S. The load port 2 includes a substantially rectangular
and vertically arranged frame 21, a table 22 horizontally provided
on the frame 21, an opening 23 that defines an opening lower edge
in the frame 21 at a height substantially the same as the table 22
and can communicate with the wafer transport chamber interior 3S, a
door section 24 that opens and closes the opening 23, and a bottom
purge apparatus 25 that injects a purge gas into the FOUP interior
5S and is capable of replacing a gaseous atmosphere in the FOUP
interior 5S with the purge gas such as nitrogen. In this
embodiment, the frame 21 is disposed such that the frame 21 is in
contact with the wafer transport chamber 3 (see FIG. 1). The table
22 is supported by a support base 26.
[0038] The door section 24 provided on the frame 21 with the FOUP 5
placed on the table 22 is movable between an opened position where
the door section 24 in close contact with the lid 52 provided on
the front face of the FOUP 5 pushes the lid 52 to open the
carrying-in/carrying-out port 51 and the opening of the FOUP 5 at
the same time, and a closed position where the door section 24
closes the carrying-in/carrying-out port 51 and the opening of the
FOUP 5. As a door elevating mechanism (not shown) for at least
vertically moving the door section 24 between the opened position
and the closed position, any known type of mechanism can be
used.
[0039] The bottom purge apparatus 25 includes a plurality of bottom
purge nozzles 251 arranged at predetermined locations with a distal
end (upper end) exposed on a top face of the table 22, and causes
each of the plurality of bottom purge nozzles 251 to function as an
injection bottom purge nozzle that injects purge gas or a discharge
bottom purge nozzle that discharges a gaseous atmosphere in the
FOUP interior 5S. The ratios of injection bottom purge nozzles and
discharge bottom purge nozzles to all the bottom purge nozzles 251
may be equal or one of the ratios may be higher than the other.
[0040] The plurality of bottom purge nozzles 251 can be attached to
appropriate positions on the table 22 corresponding to the
positions of the ports provided on the bottom 53 of the FOUP 5.
Each bottom purge nozzle 251 (injection bottom purge nozzle or
discharge bottom purge nozzle) has a valve function for regulating
backflow of gas. Note that, of the plurality of ports provided on
the bottom 53 of the FOUP 5, the port that contacts an injection
bottom purge nozzle 251 functions as an injection port, while the
port that contacts a discharge bottom purge nozzle 251 functions as
a discharge port.
[0041] In this embodiment, as illustrated in FIG. 1, with the FOUP
5 placed on the table 22, bottom purge nozzles 251 that are located
relatively farther in the front-back direction of FOUP 5 from the
opening 23 functions as injection bottom purge nozzles, and bottom
purge nozzles 251 that are located relatively closer to the opening
23 functions as discharge bottom purge nozzles. In FIG. 1, airflows
in the FOUP interior 5S are schematically illustrated by arrows
while the lid 52 of the FOUP 5 and the door section 24 of the load
port 2 are closed (door closed state).
[0042] The bottom purge nozzles 25 may be configured to be movable
up and down between a standby position where the distal end (upper
end) thereof is not in contact with the port of the FOUP 5 and a
purge position where the distal end (upper end) thereof can contact
the port of the FOUP 5. Mounted as a unit at a plurality of
predetermined locations in the table 22 of the load port 2 (for
example, near four corners of the table 22), the bottom purge
nozzles 251 function as a bottom purge apparatus 25 capable of
replacing a gaseous atmosphere in the FOUP interior 5S placed on
the table 22 with the purge gas.
[0043] The usage and action of the load port 2 including thus
configured bottom purge apparatus 25 implemented in the table 22
will now be described.
[0044] First, the FOUP 5 is transported by a transport apparatus
such as an OHT (not shown) to the load port 2 and is placed on the
table 22. The positioning protrusions for example, provided on the
table 22 fit in the positioning recesses of the FOUP 5 to allow the
FOUP 5 to be placed at a predetermined normal position on the table
22. A seating sensor (not shown) that detects whether or not the
FOUP 5 is placed at a predetermined position on the table 22 may be
configured to detect that the FOUP 5 is placed at the normal
position on the table 22. The bottom purge nozzles 251 can be
positioned at the standby position until the FOUP 5 is placed on
the table 22 of the load port 2 to avoid inadvertent contact of the
bottom purge nozzles 251 with the port of the FOUP 5.
[0045] Then the load port 2 of the embodiment moves the bottom
purge nozzles 251 up from the standby position to the purge
position to contact the lower end of the port and brings gas flow
paths formed in the bottom purge nozzles 251 into communication
with the internal space of the port in the height direction. In
this state, the load port 2 of the embodiment injects a purge gas
supplied from a source (not shown) into the FOUP interior 5S
through the gas flow paths of the purge nozzles and the internal
space of the port, discharges a gas filling the FOUP interior 5S to
outside the FOUP 5 through the discharge port and discharge bottom
purge nozzles 251. Airflows in the FOUP interior 5S at this time
are schematically illustrated by arrows in FIG. 1. Note that it is
also possible to start discharge in advance of injection, discharge
a certain amount of air in the FOUP interior 5S to outside the FOUP
5, and perform injection under reduced pressure.
[0046] The EFEM 1 according to the embodiment may start bottom
purging immediately after the FOUP 5 is received from a transport
apparatus such as an OHT onto the table 22 of the load port 2. The
bottom purging reduces the humidity and the oxygen concentration in
the FOUP interior 5S to or below a predetermined value in a short
time, respectively, so that the environment around wafers in the
FOUP interior 5S can be a lower humidity and lower oxygen
environment than that before the start of bottom purging. In this
way, with the EFEM 1 according to the embodiment, the bottom
purging by means of the bottom purge apparatus 25 provided in the
load port 2 can be effective to maintain a higher value of filling
(the degree of replacement) with purge gas in the FOUP interior 5S
than the front purging and to reduce the humidity and the oxygen
concentration in the FOUP interior 5S to or below a predetermined
value, respectively.
[0047] After the humidity and the oxygen concentration in the FOUP
interior 5S are reduced to or below a predetermined value by
performing the bottom purging as described above, the lid 52 of the
FOUP 5 is opened at the door section 24 of the load port 2 to bring
the internal space 5S of the FOUP 5 into communication with the
internal space of the semiconductor manufacturing apparatus 4
through the carrying-in/carrying-out port 51 of the load port 2 and
the opening 23 of the load port 2. In this state, wafers in the
FOUP interior 5S are sequentially expelled into the semiconductor
manufacturing apparatus 4 by the wafer transport robot located in
the wafer transport chamber interior 3S.
[0048] When the lid 52 of the FOUP 5 is opened at the door section
24 of the load port 2 to bring the internal space 5S of the FOUP 5
into communication with the internal space of the semiconductor
manufacturing apparatus 4 through the opening 23 of the load port 2
(hereinafter referred to as "door opening time point"), the gaseous
atmosphere in the wafer transport chamber interior 3S enters the
FOUP interior 5S and may cause a rapid increase in the humidity and
the oxygen concentration in the FOUP interior 5S after the door
opening time point (FIG. 2 illustrates a humidity variation by a
solid line).
[0049] In order to avoid such a situation, the EFEM 1 according to
the embodiment further includes a shield gas curtain apparatus 6
that forms a gas curtain capable of shielding the opening 23 of the
load port 2. The shield gas curtain apparatus 6 includes a shield
curtain gas blow-off section 61 that blows a shield curtain gas
composed of nitrogen or dry air immediately downward at a location
near the opening 23 of the load port 2 and being closer to the
wafer transport chamber 3 than the opening 23 at a higher height
than an upper edge of the opening 23. The shield curtain gas blown
from the shield curtain gas blow-off section 61 forms a gas curtain
capable of shielding the opening 23. The lower end (distal end) of
the shield curtain gas blow-off section 61 may be set at the same
height as the upper edge of the opening 23. The source (not shown)
of the shield curtain gas may be the same source as the purge gas
or may be separate from that of the purge gas. The source of the
shield gas and the shield curtain gas blow-off section 61 are
connected with each other through suitable pipes and joints.
[0050] Examples of the shield curtain gas blow-off section 61
include one made up of a plurality of nozzles arranged at a
predetermined interval over an area larger than the width dimension
of the opening 23 (nozzle type), and one made up of a single air
outlet whose width dimension is larger than the width dimension of
the opening 23 (blow type). When the shield curtain gas blow-off
section 61 is of a nozzle type, the shield curtain gas blown from
each of the nozzles forms a jet stream. On the other hand, when the
shield curtain gas blow-off section 61 is of a blow type, the
shield curtain gas blown from the single air outlet forms a planar
flow along a blow direction.
[0051] In the shield gas curtain apparatus 6 of the embodiment, as
illustrated in FIG. 3, the flow rate is set so that the shield
curtain gas blown from the shield curtain gas blow-off section 61
reaches down beyond the opening lower edge of the opening 23. The
airflow of such a shield curtain gas is separated from the airflow
generated by the FFU 33.
[0052] The shield gas curtain apparatus 6 is then operated at the
door opening time point or at a time point earlier than the door
opening time point to form a shield gas curtain that shields the
opening 23 of the load port 2. Accordingly, it is possible to
prevent the gaseous atmosphere in the wafer transport chamber
interior 3S from entering the FOUP interior 5S after the door
opening time point, and to prevent and suppress a rapid increase in
the humidity or the oxygen concentration in the FOUP interior 5S
occurring immediately after the door opening time point. FIG. 4
illustrates, by a long dashed short-dashed line, a humidity
variation in the FOUP interior 5S when the shield gas curtain
apparatus 6 is operated after bottom purging is performed by the
bottom purge apparatus 25 in a door closed state. Note that the
humidity variation in the FOUP interior 5S indicated in by a long
dashed short-dashed line FIG. 4 represents when the bottom purging
performed by the bottom purge apparatus 25 is continued after the
door opening time point.
[0053] As described above, the load port 2 according to the
embodiment includes a shield gas curtain apparatus 6 that forms a
gas curtain capable of shielding the opening 23 of the load port 2
when the internal space 5S of the FOUP 5 which is a purge
container, in which at least humidity is reduced to a predetermined
value (in FIG. 4, the "predetermined value" is zero or
substantially zero) by supplying the purge gas from the bottom
purge apparatus 25, is brought into communication with the internal
space 3S of the wafer transport chamber 3 through the opening 23
(time t1 in FIG. 4), the gas curtain being formed of a shield
curtain gas composed of nitrogen or dry air blown immediately
downward from a location near the opening 23 and being closer to
the wafer transport chamber 3 than the opening 23 at the same
height as or a higher height than an upper edge of the opening 23.
As a result, in the door closed state where the internal space 5S
of the FOUP 5 is not in communication with the internal space 3S of
the wafer transport chamber 3, the humidity in the internal space
5S of the FOUP 5 can be reduced to or below the predetermined value
by the bottom purge apparatus 25. Even in the door open state where
the internal space 5S of the FOUP 5 is in communication with the
internal space 3S of the wafer transport chamber 3, it is possible
to prevent and suppress the gaseous atmosphere in the wafer
transport chamber interior 3S from entering a low humidity and low
oxygen environment of the FOUP interior 5S by forming a gas curtain
by the shield gas curtain apparatus 6. In addition, after the door
opening time point (for example, time t1 indicated in FIG. 4), the
humidity in the FOUP interior 5S can be maintained in a range
(allowable humidity range) low enough to prevent and suppress
adherence of moisture onto a wafer in the FOUP interior 5S, so that
quality degradation due to the moisture adhered on a wafer can
be
[0054] As illustrated in FIG. 4, although the humidity in the FOUP
interior 5S may somewhat increase after the door opening time point
even when a gas curtain is formed by the shield gas curtain
apparatus 6, a peak will be reached at some point in time and the
peak value P will not be exceeded. When the peak value P represents
a humidity enough to prevent and suppress adherence of moisture
onto a wafer in the FOUP interior 5S, in view of this point and as
illustrated in FIG. 5, during a process of bottom purging by means
of the bottom purge apparatus 25 to gradually reduce the humidity
in the FOUP interior 5S with the lid 52 of the FOUP 5 closed, wafer
transportation can be started at a time t2 when the humidity
reaches the same level as the above-described peak value P by
opening the lid 52 of the FOUP 5 with the door section 24 of the
load port 2 so as to bring the FOUP 5 into communication with the
internal space 3S of the wafer transport chamber 3 through the
opening 23 of the load port 2. Consequently, the peak value P can
be considered as a "predetermined value" of the present invention.
When the bottom purging and the shield curtain gas blowing are
performed at the same time, a peak value P at which the humidity in
the FOUP 5 reaches the highest can be determined in advance. Then,
the bottom purging by means of the bottom purge apparatus 25 is
performed with the lid 52 of the FOUP 5 closed to reduce the
humidity in the FOUP interior 5S to the peak value P, instead of
reducing it to zero or approximately zero. In this state, when the
bottom purging and the shield curtain gas blowing are continued
after the time point t2 when the peak value P has been reached, the
humidity in the FOUP interior 5S will no longer increase further.
Then, the time point t2, at which the humidity in the FOUP interior
5S is reduced to the peak value P, can be selected as a timing for
opening the lid 52 of the FOUP 5, instead of the time point t1, at
which the humidity is reduced to zero or approximately zero with
the lid 52 of the FOUP 5 closed. As a result, time needed from when
the FOUP 5 is received on the table 22 at the load port 2 from a
transport apparatus such as an OHT to when the lid 52 of the FOUP 5
is opened can be reduced, leading to tact time reduction, and
consequently, an improved efficiency of wafer processing.
[0055] Another embodiment (hereinafter referred to as a second
embodiment) different from the embodiment described above (which is
a first embodiment) will now be described with reference to FIGS. 6
and 7 among others.
[0056] The second embodiment is different from the first embodiment
in that a shield gas curtain apparatus 27 is provided on the load
port 2. Accordingly, although the configuration of the load port 2
will be detailed below, description on the wafer transport chamber
3 and the semiconductor manufacturing apparatus 4 will be
omitted.
[0057] As illustrated in FIGS. 6 and 7, the load port 2 according
to the embodiment is used to open and close a lid 52 of the FOUP 5
in a close contact state and allow a wafer to be exchanged between
the FOUP interior 5S and the wafer transport chamber interior 3S.
The load port 2 includes a substantially rectangular and vertically
arranged frame 21, a table 22 horizontally provided on the frame
21, an opening 23 that defines an opening lower edge in the frame
21 at a height substantially the same as the table 22 and can
communicate with the wafer transport chamber interior 3S, a door
section 24 that opens and closes the opening 23, a bottom purge
apparatus 25 that injects a purge gas into the FOUP interior 5S and
is capable of replacing a gaseous atmosphere in the FOUP interior
5S with the purge gas such as nitrogen, a support base 26
supporting the table 22, and a shield gas curtain apparatus 27 that
forms a gas curtain capable of shielding the opening 23.
[0058] The door section 24 provided on the frame 21 is with the
FOUP 5 placed on the table 2 movable between an opened position
where the door section 24 in close contact with the lid 52 provided
on the front face of the FOUP 5 pushes the lid 52 to open the
carrying-in/carrying-out port 51 and the opening of the FOUP 5 at
the same time and a closed position where the door section 24
closes the carrying-in/carrying-out port 51 and the opening of the
FOUP 5. As a door elevating mechanism (not shown) for at least
vertically moving the door section 24 between the opened position
and the closed position, any known type of mechanism can be
used.
[0059] The bottom purge apparatus 25 includes a plurality of bottom
purge nozzles 251 arranged at predetermined locations with an upper
end (distal end) exposed on a top face of the table 22, and causes
each of the plurality of bottom purge nozzles 251 to function as an
injection bottom purge nozzle that injects purge gas or a discharge
bottom purge nozzle that discharges a gaseous atmosphere in the
FOUP interior 5S. The ratios of injection bottom purge nozzles and
discharge bottom purge nozzles to all the bottom purge nozzles 251
may be equal or one of the ratios may be higher than the other.
[0060] The plurality of bottom purge nozzles 251 can be attached to
appropriate positions on the table 22 corresponding to the
positions of the ports provided on the bottom 53 of the FOUP 5.
Each bottom purge nozzle 251 (injection bottom purge nozzle or
discharge bottom purge nozzle) has a valve function for regulating
backflow of gas and can be brought into contact with ports provided
on the bottom 53 of the FOUP 5. Note that, of the plurality of
ports provided on the bottom 53 of the FOUP 5, the port that
contacts an injection bottom purge nozzle functions as an injection
port, while the port that contacts a discharge bottom purge nozzle
functions as a discharge port.
[0061] In this embodiment, as illustrated in FIG. 6, bottom purge
nozzles 251 that are located relatively farther in the front-back
direction of FOUP from the opening 23 function as injection bottom
purge nozzles, and bottom purge nozzles 251 that are located
relatively closer to the opening 23 function as discharge bottom
purge nozzles. In FIG. 6, airflows in the FOUP interior 5S are
schematically illustrated by arrows while the lid 52 of the FOUP 5
and the door section 24 of the load port 2 are closed (door closed
state).
[0062] The bottom purge nozzles 251 may be configured to be movable
up and down between a standby position where the distal end (upper
end) thereof is not in contact with the port of the FOUP 5 and a
purge position where the distal end (upper end) thereof can contact
the port of the FOUP 5. Mounted as a unit at a plurality of
predetermined locations in the table 22 of the load port 2 (for
example, near four corners of the table 22), the bottom purge
nozzles 251 function as a bottom purge apparatus 25 capable of
replacing a gaseous atmosphere in the FOUP interior 5S placed on
the table 22 with the purge gas.
[0063] The shield gas curtain apparatus 27 includes a shield
curtain gas blow-off section 271 that blows a shield curtain gas
composed of nitrogen or dry air immediately downward at a location
near the opening 23 of the load port 2 and being closer to the
wafer transport chamber 3 than the opening 23 at a higher height
than an upper edge of the opening 23. The shield curtain gas blown
from the shield curtain gas blow-off section 271 forms a gas
curtain capable of shielding the opening 23. The lower end (distal
end) of the shield curtain gas blow-off section 271 may be set at
the same height as the upper edge of the opening 23. The source
(not shown) of the shield curtain gas may be the same source as the
purge gas or may be separate from that of the purge gas. The source
of the shield gas and the shield curtain gas blow-off section 271
are connected with each other through suitable pipes and
joints.
[0064] Examples of the shield curtain gas blow-off section 271
include one made up of a plurality of nozzles arranged at a
predetermined interval over an area larger than the width dimension
of the opening 23 (nozzle type), and one made up of a single air
outlet whose width dimension is larger than the width dimension of
the opening 23 (blow type). The shield curtain gas blow-off section
271 of a nozzle type causes the shield curtain gas blown from each
of the nozzles to form a jet stream. On the other hand, the shield
curtain gas blow-off section 271 of a blow type causes the shield
curtain gas blown from the single air outlet to form a planar flow
along a blow direction.
[0065] In the shield gas curtain apparatus 27 of the embodiment, as
illustrated in FIG. 7, the flow rate is set so that the shield
curtain gas blown from the shield curtain gas blow-off section 271
reaches down beyond the opening lower edge of the opening 23. The
airflow of such a shield gas curtain is separated from the airflow
generated by the FFU 33.
[0066] The usage and action of the load port 2 including the bottom
purge apparatus 25 and the shield gas curtain apparatus 27 as
described above implemented therein will now be described.
[0067] First, the FOUP 5 is transported by a transport apparatus
such as an OHT (not shown) to the load port 2 and is placed on the
table 22. The positioning protrusions provided on the table 22 fit
in the positioning recesses of the FOUP 5 to allow the FOUP 5 to be
placed at a predetermined normal position on the table 22. A
seating sensor (not shown) that detects whether or not the FOUP 5
is placed at a predetermined position on the table 22 may be
configured to detect that the FOUP 5 is placed at the normal
position on the table 22. The bottom purge nozzles 251 are
positioned at the standby position until the FOUP 5 is placed on
the table 22 of the load port 2 to avoid inadvertent contact of the
bottom purge nozzles 251 with the port of the FOUP 5.
[0068] Then the load port 2 according to the embodiment moves the
bottom purge nozzles 251 up from the standby position to the purge
position to contact the lower end of the port and brings gas flow
paths formed in the bottom purge nozzles 251 into communication
with the internal space of the port in the height direction. In
this state, the load port 2 according to the embodiment injects a
purge gas supplied from a source (not shown) into the FOUP interior
5S through the gas flow paths of the purge nozzles and the internal
space of the port, discharges a gas filling the FOUP interior 5S to
outside the FOUP 5 through the discharge port and discharge bottom
purge nozzles 251. Airflows in the FOUP interior 5S at this time
are schematically illustrated by arrows in FIG. 6. Note that it is
also possible to start discharge in advance of injection, discharge
a certain amount of air in the FOUP interior 5S to outside the FOUP
5, and perform injection under reduced pressure.
[0069] The load port 2 according to the embodiment may start bottom
purging immediately after the FOUP 5 is received from a transport
apparatus such as an OHT onto the table 22. The bottom purging
reduces the humidity and the oxygen concentration in the FOUP
interior 5S to or below a predetermined value in a short time,
respectively, so that the environment around wafers in the FOUP
interior 5S can be a lower humidity environment than that before
the start of bottom purging. In this way, with the load port 2
according to the embodiment, the bottom purging by means of the
bottom purge apparatus 25 can be effective to maintain a higher
value of filling (the degree of replacement) with purge gas in the
FOUP interior 5S than the front purging, and to reduce the humidity
and the oxygen concentration in the FOUP interior 5S to or below a
predetermined value, respectively.
[0070] After the humidity and the oxygen concentration in the FOUP
interior 5S are reduced to or below a predetermined value by
performing the bottom purging as described above, the lid 52 of the
FOUP 5 is opened at the door section 24 of the load port 2 to bring
the internal space 5S of the FOUP 5 into communication with the
internal space of the semiconductor manufacturing apparatus 4
through the carrying-in/carrying-out port 51 of the load port 2 and
the opening 23 of the load port 2. In this state, wafers in the
FOUP interior 5S are sequentially expelled into the semiconductor
manufacturing apparatus 4 by the wafer transport robot located in
the wafer transport chamber interior 3S.
[0071] In the load port 2 according to the embodiment, the shield
gas curtain apparatus 27 is then operated at the door opening time
point or at a time point earlier than the door opening time point
to form a shield gas curtain that shields the opening 23 of the
load port 2, so as to prevent the gaseous atmosphere in the wafer
transport chamber interior 3S from entering the FOUP interior 5S
after the door opening time point, and to prevent and suppress a
rapid increase in the humidity or the oxygen concentration in the
FOUP interior 5S occurring immediately after the door opening time
point. FIG. 4 illustrates, by a long dashed short-dashed line, a
humidity variation in the FOUP interior 5S when the shield gas
curtain apparatus 27 is operated after bottom purging is performed
by the bottom purge apparatus 25 in a door closed state. The
humidity variation in the FOUP interior 5S indicated by a long
dashed short-dashed line in FIG. 4 represents when the bottom
purging performed by the bottom purge apparatus 25 is continued
after the door opening time point.
[0072] As described above, the EFEM 1 and the load port 2 according
to the embodiment includes a shield gas curtain apparatus 27 that
forms a gas curtain capable of shielding the opening 23 of the load
port 2 when the internal space 5S of the FOUP 5 which is a purge
container, in which at least humidity is reduced to a predetermined
value (in FIG. 4, the "predetermined value" is zero or
substantially zero) by supplying the purge gas from the bottom
purge apparatus 25, is brought into communication with the internal
space 3S of the wafer transport chamber 3 through the opening 23,
the gas curtain being formed of a shield curtain gas composed of
nitrogen or dry air blown immediately downward from a location near
the opening 23 and being closer to the wafer transport chamber 3
than the opening 23 at the same height as or a higher height than
an upper edge of the opening 23. As a result, in the door closed
state where the internal space 5S of the FOUP 5 is not in
communication with the internal space 3S of the wafer transport
chamber 3, the humidity in the internal space 5S of the FOUP 5 can
be reduced to or below the predetermined value by the bottom purge
apparatus 25. Even in the door open state where the internal space
5S of the FOUP 5 is in communication with the internal space 3S of
the wafer transport chamber 3, it is possible to prevent and
suppress the gaseous atmosphere in the wafer transport chamber
interior 3S from entering a low humidity and low oxygen environment
of the FOUP interior 5S by forming a gas curtain by the shield gas
curtain apparatus 27. In addition, after the door opening time
point (for example, time t1 indicated in FIG. 4), the humidity in
the FOUP interior 5S can be maintained in a range (allowable
humidity range) low enough to prevent and suppress adherence of
moisture onto a wafer, so that quality degradation due to the
moisture adhered on a wafer can be avoided.
[0073] As illustrated in FIG. 4, although the humidity in the FOUP
interior 5S may somewhat increase after the door opening time point
even when a gas curtain is formed by the shield gas curtain
apparatus 27, a peak will be reached at some point in time and the
peak value P will not be exceeded. When the peak value P represents
a humidity enough to prevent and suppress adherence of moisture
onto a wafer in the FOUP interior 5S, in view of this point and as
illustrated in FIG. 5, during a process of bottom purging by means
of the bottom purge apparatus 25 to gradually reduce the humidity
in the FOUP interior 5S with the lid 52 of the FOUP 5 closed, wafer
transportation can be started at a time t2 when the humidity
reaches the same level as the above-described peak value P by
opening the lid 52 of the FOUP 5 with the door section 24 of the
load port 2 so as to bring the FOUP 5 into communication with the
internal space 3S of the wafer transport chamber 3 through the
opening 23 of the load port 2. Consequently, the peak value P can
be considered as a "predetermined value" of the present invention.
When the bottom purging and the shield curtain gas blowing are
performed at the same time, a peak value P at which the humidity in
the FOUP interior 5S reaches the highest can be determined in
advance. Then, the bottom purging by means of the bottom purge
apparatus 25 is performed with the lid 52 of the FOUP 5 closed to
reduce the humidity in the FOUP interior 5S to the peak value P,
instead of reducing it to a predetermined value of zero or
approximately zero. In this state, when the bottom purging and the
shield curtain gas blowing are continued after the time point t2
when the peak value P has been reached, the humidity in the FOUP
interior 5S will no longer increase further. Then, the time point
t2, at which the humidity in the FOUP interior 5S is reduced to the
peak value P, can be selected as a timing for opening the lid 52 of
the FOUP 5, instead of the time point t1, at which the humidity is
reduced to zero or approximately zero with the lid 52 of the FOUP 5
closed. As a result, time needed from when the FOUP 5 is received
on the table 22 at the load port 2 from a transport apparatus such
as an OHT to when the lid 52 of the FOUP 5 is opened can be
reduced, leading to tact time reduction, and consequently, an
improved efficiency of wafer processing.
[0074] In any of the embodiments described above (the first and
second embodiments), each wafer transferred into the semiconductor
manufacturing apparatus 4 is then subjected to a semiconductor
manufacturing process by the semiconductor manufacturing apparatus
main body 41. The wafers having undergone the semiconductor
manufacturing process by the semiconductor manufacturing apparatus
main body 41 are sequentially stored in the FOUP 5. When all the
wafers have undergone the semiconductor manufacturing process and
are stored in the FOUP 5, the door section 24 is moved from the
opened position to the closed position while the door section 24 is
in close contact with the lid 52 of the FOUP 5. As a result, the
opening 23 of the load port 2 and the carrying-in/carrying-out port
51 of the FOUP 5 are closed, and the FOUP 5 on the table 22 is then
carried out by a transport mechanism (not shown) to a next
process.
[0075] Note that the present invention is not limited to the
above-described embodiments. For example, although a FOUP is
illustrated as a purge container in the above-described
embodiments, any other container (carrier) may be used as the purge
container.
[0076] Applicable shield gas curtain apparatuses may include one
that forms a gas curtain capable of shielding the opening by means
of a shield curtain gas blown obliquely downward such that the gas
diverges from the purge container. The gas curtain formed by such a
shield gas curtain apparatus can prevent and suppress the entrance
of the gas in the wafer transport chamber into the purge container
in the door open state. In this case, the shield curtain gas
blow-off section of the shield gas curtain apparatus may also be
either a nozzle type or a blow type.
[0077] The specific configuration of each section is not limited to
the above embodiments, and various modifications can be made
without departing from the scope of the present invention.
* * * * *