Gas separation – Combined or convertible
Reexamination Certificate
2001-11-20
2003-12-30
Copenheaver, Blaine (Department: 1724)
Gas separation
Combined or convertible
C055S323000, C055S329000, C055S392000, C055S429000, C096S400000, C096S421000, C454S354000
Reexamination Certificate
active
06669750
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to an access port for a house vacuum system used in a semiconductor fabrication facility and more particularly, relates to an access port for a house vacuum system that is equipped with a removable trap for preventing the access port from being plugged up by the vacuumed debris.
BACKGROUND OF THE INVENTION
In the recent development of semiconductor fabrication technology, the continuous miniaturization in device fabricated demands more stringent requirements in the fabrication environment and contamination control. When the feature size was in the 2 &mgr;m range, a cleanliness class of 100-1000 (which means the number of particles at sizes larger than 0.5 &mgr;m per cubic foot) was sufficient. However, when the feature size is reduced to 0.25 &mgr;m, a cleanliness class of 0.1 is required. It has been recognized that an inert mini-environment may be the only solution to future fabrication technologies when the device size is reduced further. In order to eliminate micro-contamination and to reduce native oxide growth on silicon surfaces, the wafer processing and the loading/unloading procedures of a process tool must be enclosed in an extremely high cleanliness mini-environment that is constantly flush with ultrapure nitrogen that contains no oxygen and moisture.
Different approaches in modern cleanroom design have been pursued in recent years with the advent of the ULSI technology. One is the utilization of a tunnel concept in which a corridor separates the process area from the service area in order to achieve a higher level of air cleanliness. Under the concept, the majority of equipment maintenance functions are conducted in low-classified service areas, while the wafers are handled and processed in more costly high-classified process tunnels. For instance, in a process for 16M and 64M DRAM products, the requirement of contamination control in a process environment is so stringent that the control of the enclosure of the process environment for each process tool must be considered. This stringent requirement creates a new mini-environment concept which is shown in FIG.
1
A. Within the enclosure of the mini-environment of a process tool
10
, an extremely high cleanliness class of 0.1 (which means the number of particles at sizes larger than 0.1 &mgr;m per cubic foot) is maintained, in contrast to a cleanliness class of 1000 for the overall production cleanroom
12
. In order to maintain the high cleanliness class inside the process tool
10
, the loading and unloading sections
14
of the process tool must be handled automatically by an input/output device such as a SMIF (standard mechanical interfaces) apparatus. A cassette or wafer can be transported into the process tool
10
by SMIF pod
18
situated on top of the SMIF apparatus
20
.
Also provided in the cleanroom
12
is a house vacuum system equipped with a vacuum access port
40
shown in
FIGS. 1A-1C
. The vacuum access port
40
is constructed by a vacuum conduit
42
and a cover assembly
44
. The house vacuum system is provided with the vacuum access port
40
throughout a cleanroom, which is normally installed in the cleanroom floor such that a top surface of the cover assembly
44
is flush with the top surface
32
of the cleanroom floor. The purpose of the house vacuum system is to provide ready access to a factory vacuum source for cleaning of process tools or work areas. The vacuum conduit
42
is provided with an apertured plate
50
with a plurality of apertures
52
therein for filtering out or stopping large debris that are vacuumed into the conduit
42
.
The cover assembly
44
for the vacuum access port
40
is shown in detail in
FIG. 1B
in a perspective view. The cover assembly
44
is normally provided with a recess
34
in a top surface
36
of the cover assembly
44
. The recess
34
is further provided with a pin
38
for grasp by a pair of pincers during a preventive maintenance procedure. The cover assembly
44
is constructed by an upper portion
46
and a lower portion
48
that are both formed in an annular shape. The outside diameter of the lower portion
48
is only slightly smaller than the inside diameter of the conduit
42
such that a snug fit can be achieved for a vacuum-tight seal.
FIG. 1C
illustrates a cross-sectional view of the cover assembly
44
installed in the vacuum conduit
42
.
The cover assembly
44
illustrated in
FIGS. 1A-1C
serves the purpose of sealing a vacuum outlet
40
. However, whenever an operator needs to use the house vacuum by attaching a vacuum hose connector to the conduit
42
, a pair of pincers or Allen wrench must be used to pick up the cover assembly
44
by the pin
38
. This process must be repeated several times a day whenever a process chamber, or a work area needs to be cleaned. Moreover, the apertured plate
50
used in the vacuum conduit
42
for filtering out the debris from vacuuming can be easily plugged up such that the vacuum operation cannot be efficiently conducted. The plurality of apertures
52
in the apertured plate
50
can be easily jammed or blocked by the debris picked up during vacuuming. The removal of the debris from cavity
54
is inconvenient and awkward to access. Major improvements to the conventional vacuum conduit system and the vacuum access port are therefore needed for providing easy access to the house vacuum in a cleanroom.
It is therefore an object of the present invention to provide an access port for a house vacuum system that does not have the drawbacks or shortcomings of the conventional access ports.
It is another object of the present invention to provide an access port for a house vacuum system that is equipped with a removable trap for easier removal of vacuumed debris.
It is a further object of the present invention to provide an access port for a house vacuum system that includes a hinged cover for easier access.
It is another further object of the present invention to provide a portable vacuum access port for a house vacuum system wherein the access port protrudes above the floor panel.
It is still another object of the present invention to provide a vacuum access port for a house vacuum system equipped with a removable trap provided with a plurality of apertures both in a bottom and in a sidewall of the trap.
SUMMARY OF THE INVENTION
In accordance with the present invention, an access port for a house vacuum system that is equipped with a removable trap is disclosed.
In a preferred embodiment, an access port for a house vacuum system that is equipped with a removable trap is provided which includes a port body of elongated, cylindrical shape that has an open top and an apertured bottom in fluid communication with a vacuum source; a port cover pivotally connected to a floor panel by hinge means, the port cover has an outer dimension that is at least the outer dimension of the port body for sealingly engaging an upper rim of the port body when the port cover is in a closed position; a debris trap of elongated, cylindrical shape removably mounted inside the port body for collecting debris from a vacuuming operation and for allowing air to pass therethrough through a plurality of apertures provided in a sidewall and in a bottom plate of the debris trap; and a vacuum hose access means in the port cover for sealingly connecting a vacuum hose to a vacuum source.
In the access port for a house vacuum system, the vacuum hose access means may include a vacuum hose access port in the port cover and a cover for the vacuum hose access port pivotally connected to the port cover by a hinge means. The vacuum hose access port may be equipped with a downwardly projecting sidewall for frictionally engaging an outer peripheral surface of a vacuum hose when the cover for the access port is pivotally opened. The vacuum hose access means may further include a vacuum hose access port in the port cover and a cover for sealing the vacuum hose access port when the vacuum hose is not in use. The vacuum hose access port may be formed of an opening and an upwardly
Chen Wan-ly
Chen Yeay-Cin
Hsu Jun-Sheng
Liao Jason
Copenheaver Blaine
Pham Minh-Chau T.
Taiwan Semiconductor Manufacturing Co. Ltd
Tung & Associates
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