Pipe joints or couplings – Variable length
Reexamination Certificate
2000-08-11
2002-07-23
Nicholson, Eric K. (Department: 3627)
Pipe joints or couplings
Variable length
C285S187000, C285S224000
Reexamination Certificate
active
06422610
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a fluid supply line used in a semiconductor fabrication facility and more particularly, relates to a deformable fluid supply line used in a semiconductor fabrication facility that is capable of surviving a low level of deformation without damages and a method for shock-proving a fluid supply line.
BACKGROUND OF THE INVENTION
In the semiconductor process industry, a large variety of different ultrapure gasses are used in the fabrication plants. These gases include bulk gases such as N
2
, O
2
, H
2
and Ar which are normally used in very large quantities, and specialty gases such as He, A
2
F
3
, PH
3
, SiH
4
, NH
2
and NF
3
which are used only in small quantities. In general, the bulk gases are used for purging of chambers, oxidation and cleaning of cleaning of wafers, while the specialty gases are used as reactant or etching gases.
The bulk gases are normally stored in large storage facilities, for instance N
2
can be supplied from a liquified-nitrogen storage tank located in the gas yard or delivered from a pipeline from a remote air-separation; O
2
and Ar can be supplied from liquified gas storage tanks; while H
z
can be delivered from either a liquified-gas storage tank or a bank of high-pressure gas cylinders. The bulk gases are normally passed through purifiers and gas filters for removing impurities and contaminating particles before allowed to enter a gas-distribution piping system installed inside a cleanroom. On the other hand, the specialty gases are normally stored in small quantities in gas cylinders and are sent directly to the process tools from cylinders stored inside gas cabinets in the cleanroom. The gas cabinets are exhausted safety enclosures that contain the gas cylinders and the necessary gas handling equipment. The gas cabinets serve a major function of allowing purging and safe exchange of the specialty gas cylinders. The gas handling equipment, which includes gas panels incorporating all components for the control and monitoring of high purity gases. In most semiconductor fabrication facilities, the gas cabinet contains at least two process cylinders to allow easy switch-over when one cylinder is empty. In addition, another cylinder of inert gas such as nitrogen is provided for purging the piping line.
In most fabrication processes, the supply pressure for the bulk and the specialty gases is kept at under 10 Kg/cm
2
. A few exceptions exist such as chlorine and dichlorosilane. At each point of use, the pressure of the bulk or specialty gas has to be independently and locally controlled by a series of flow control valves, pressure regulators, pressure sensors and particle filters located inside a gas manifold box. The precise pressure required for each bull: or specialty gases to be delivered to a specific process tool is determined by the process requirement. In most semiconductor cleanroom facility; one or more gas manifold boxes are installed nearby to each process tool to facilitate gas distribution and control.
A typical bulk gas distribution system
10
is shown in FIG.
1
. The gas distribution system
10
is used, for instance, to distribute an inert gas such as helium. The system
10
consists essentially of two gas supply sources, i.e. a main gas supply source
12
which is a trailer mounted gas source and a back-up gas supply source
14
which is a plurality of gas cylinders with their outlets
16
parallelly connected. The gas from the main gas supply source
12
is fed to a three-way flow control valve
18
through conduit
22
. The conduit
22
further includes flow control valves, pressure regulators, pressure sensors and particle filters which are not shown for simplicity reasons. The back-up gas supply source
14
is also connected to the three-way flow control valve
18
through conduit
24
for feeding a gas to the process tool
20
through the three-way flow control valve
18
when the valve is manually switched over upon an indication that the pressure of the main gas supply source
12
has dropped to a level that requires replacement. The conduit
24
further includes flow control valves, pressure sensors, pressure regulators and particle filters which are not shown. Conduit
20
feeds the process gas to process tool
30
.
The conduit
20
that feeds the process gas to process tool
30
is normally provided in one-half inch diameter stainless steel piping that has a length of several tens of meters long. For instance, it is not uncommon to have process gas delivered to a process machine through pipes of 40 or 50 meter length. The length of tubing is set up in a straight line with bends of 90° to reach its destiny i.e, the process machine. It has been found that when a displacement of the process machine, or otherwise the piping has occurred, the piping itself may be fractured or the connection between the piping and the process machine may be damaged and thus causing a leak of the process gas. The displacement of the gas feed pipe and/or the process machine can easily occur in a fabrication facility due to mis-handling of the equipment. In certain geographical area, i.e. in California or in certain Asian Pacific regions, earthquake frequently occurs to present a great potential for such displacements. It is therefore desirable to provide gas feeding pipes that can be used to absorb shock or deformation due to mishandling of the equipment or due to earthquake.
Attempts such as using bellows in gas supply lines for absorbing shock, displacement or defamation have been made by others. However, since bellows are frequently fabricated of materials having a smaller thickness, i.e. in order to provide flexibility, they can be easily damaged by mis-handling by an operator or by displacement caused by an earthquake. The use of bellows is therefore inadequate to prevent damages to gas supply lines.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a deformable fluid supply line for use in a semiconductor fabrication facility that does not have the drawbacks or shortcomings of the conventional fluid supply lines.
It is another object of the present invention to provide a deformable fluid supply line for use in a semiconductor fabrication facility that incorporates generally S-shaped expandable joints.
It is a further object of the present invention to provide a deformable fluid supply line for use in a semiconductor fabrication facility by using generally S-shaped expandable joint that is capable of deforming at least 2 cm without breaking from the supply line.
It is another further object of the present invention to provide a deformable fluid supply line for a semiconductor fabrication machine which contains generally S-shaped expandable joints that have a length of at least 10 cm.
It is still another object of the present invention to provide a deformable fluid supply line incorporating at least one deformable joint therein that is capable of surviving a low level earthquake without incurring damages.
It is yet another object of the present invention to provide a deformable fluid supply line incorporating at least one deformable joint therein which is capable of being deformed by at least 2.0 cm when the length of the deformable joint is 10 cm.
It is still another further object of the present invention to provide a method for connecting a deformable fluid supply line to a fabrication machine by providing a generally S-shaped deformable joint connected in series with the fluid supply line.
It is yet another further object of the present invention to provide a method for connecting a deformable supply line to a semiconductor fabrication machine by incorporating a generally S-shaped deformable joint connected in series with the supply line that survives a defamation of at least 2 cm without breaking connections with the supply line.
In accordance with the present invention, a deformable fluid supply line for use in a semiconductor fabrication machine and a method for connecting a deformable fluid supply line to a fabrication machine ar
Nicholson Eric K.
Taiwan Semiconductor Manufacturing Co. Ltd
Tung Randy W.
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