Ventilation – Clean room
Reexamination Certificate
1999-06-23
2002-02-19
Joyce, Harold (Department: 3749)
Ventilation
Clean room
C414S217000, C414S940000
Reexamination Certificate
active
06347990
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to microelectronic fabrication systems, and more particularly to methods and systems for cleaning microelectronic fabrication systems.
BACKGROUND OF THE INVENTION
Microelectronic fabrication systems are widely used to fabricate microelectronic devices such as microelectronic wafers, integrated circuits and liquid crystal display panels. Tile environment of a microelectronic fabrication process generally must be maintained in a very clean state, in order to allow high yields of microelectronic devices. In general, as microelectronic devices become more highly integrated, a higher degree of cleanness may be required.
A unit process region where a specific process is performed on a microelectronic substrate such as a wafer, generally includes a wafer process area where a predetermined operation is performed on the wafer and a wafer transfer area where the wafer is loaded/unloaded to/from the wafer process area. The unit process region is located in a service area of the microelectronic fabrication system
The unit process region generally adjoins a working area which is also referred to as a bay. After a boat having wafers mounted thereon is moved from the working area to the wafer transfer area by an operator, a robot in the wafer transfer area loads wafers one by one from the boat to the wafer process area. The robot in the water transfer area also performs an unloading operation of wafers from the wafer process area, after processing has been performed.
FIGS. 1 and 2
are a top view and a side view of a layout of a conventional microelectronic fabrication system.
In
FIGS. 1 and 2
, reference numeral
1
denotes a clean room that is isolated from the outside environment and that includes a working area
10
and a service area
20
. In the clean room
1
, the temperature and the humidity are controlled and particle-removed clean air flows downward.
An upper plenum
2
for supplying clean air is placed in the upper portion of the clean room
1
, and a lower plenum
3
for recovering the air that passes through the clean room
1
is placed in the lower portion thereof. The clean air supplied from the upper plenum
2
passes through the working area
10
and the service area
20
via a filter. Fine particles generated in the working area
10
and in the service area
20
are exhausted through the lower plenum
3
that is maintained at a low pressure, together with the clean air.
The clean room
1
is maintained at a pressure higher than the atmospheric pressure so that external air is not induced inside. Also, the pressure of the working area
10
is adjusted to be higher than that of the service area
20
. This can prevent the fine particles generated in the service area
20
from being induced into the working area
10
, due to the pressure difference. The pressure difference is controlled by adjusting the amount and/or velocity of clean air flowing through the working area
10
and the service area
20
.
In
FIG. 2
, arrows indicate a direction of flow of the clean air. The upper and lower plenums
2
and
3
of the clean room
1
are isolated from each other by respective filters
2
a
for removing particles contained in the air and gratings
3
a
having openings through which the air passes. The amount of flow of the clean air in the working area
10
and the service area
20
may be adjusted by the sizes of the filters
2
a
, the number of gratings
3
a
and/or the number of openings formed in the gratings
3
a.
As described above, since more air flows into the working area
10
than into the service area
20
and the working area
10
is maintained at a pressure higher than the service area
20
, the air flows from the working area
10
to the service area
20
. The air flow between the working area
10
and the service area
20
occurs via a wall
4
which isolates the working area
10
and the service area
20
from each other.
The wall
4
between the working area
10
and the service area
20
includes a plurality of members having gaps
4
a
large enough to allow the air to flow therethrough. Thus, some of the clean air flowing in the working area
10
of the clean room spontaneously flows to the service area
20
through the gaps
4
a
in the wall
4
. The air flows between a wafer process area
31
where a predetermined process is performed on a wafer, and a wafer transfer area
32
where wafers are loaded/unloaded to/from the wafer process area
31
.
An opening or a boat gate
4
b
for ingress or egress of a boat having a plurality of wafers mounted thereon is provided between the wafer transfer area
32
and the working area
10
. An opening or a wafer gate
32
a
for ingress or egress of wafers is provided between the wafer process area
31
and the water transfer area
32
. Doors for opening/closing the gates
4
b
and
32
a
are provided in the gates
4
b
and
32
a
. Gaps which allow a flow of air are present around the doors of the gates
4
b
and
32
a.
According to the above-described structure, the air flows inside the process region
30
. In particular, clean air is induced from the working area
10
maintained at a high pressure, to the wafer transfer area
32
through the gaps of the boat gate
4
b
or other openings present in the process region
30
. The clean air induced into the wafer transfer area
32
penetrates to the wafer process area
31
through the wafer gate
32
a.
Then, the clean air induced to the wafer process area
31
is exhausted to the service area
20
through openings present around the wafer process area or a gap
31
a
. As described above, the flow of air inside the process region
30
occurs due to a pressure difference between the working area
10
and the service area
20
.
As shown in
FIG. 3
, an air-supplying device
50
for supplying purified clean air to the wafer process area
31
and the wafer transfer area
32
may be installed in the process region
30
.
Referring to
FIG. 3
, the air-supplying device
50
absorbs clean air from the working area
10
through an induction pipe
51
, purifies the clean air physically and/or chemically and then supplies the purified clean air to the wafer process area
31
and the wafer transfer area
32
as shown by arrows
52
and
53
respectively. Alternatively, the air-supplying device
50
may be installed in the lower plenum
3
so that the air is induced therefrom, rather than from the working area
10
. The flow of air supplied to the wafer process area
31
and the wafer transfer area
32
by the air-supplying device
50
is performed in a direction adapted to maintain the flow of air from the working area
10
at a higher pressure than the service area
20
.
Thus, as described above with reference to
FIG. 2
, while purified clean air is supplied to the wafer process area
31
and the wafer transfer area
32
by the air-supplying device
50
, the air also is induced from the working area
10
to the wafer transfer area
32
through the boat gate
4
b
. Then, air penetrates from the wafer transfer area
32
to the wafer process area
31
through the wafer gate
32
a
. Clean air induced to the wafer process area
31
is exhausted to the service area
20
through openings present around the wafer process area
31
or the gap
31
a.
Notwithstanding these and other improvements in systems and methods for cleaning microelectronic fabrication systems, there continues to be a need for systems and methods for further improving the cleanliness of microelectronic fabrication systems.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide methods and systems for cleaning microelectronic fabrication systems.
It is another object of the present invention to provide microelectronic system cleaning methods and systems that can reduce contamination of microelectronic devices.
It is another object of the present invention to provide microelectronic fabrication system cleaning methods and systems that can improve the yield of microelectronic devices.
These and other objects are provided, according to the present inv
Han Sam-soon
Lee Kang-sik
Oh Chang-wook
Sung Woo-dong
Joyce Harold
Myers Bigel & Sibley & Sajovec
Samsung Electronics Co,. Ltd.
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