semi合集-English.pdf - 第3810页

SEMI F13-1101 © SEMI 199 3, 2001 4 7.1.3 E xcess Pre ssure Co ntrol — Prov isions should be made to protect the dis tribution pipi ng and process equipment from excessive pressure. This protection may include a press ure…

100%1 / 7923
SEMI F13-1101 © SEMI 1993, 20013
different mixture ratios of the same process gas class. A
check valve should be installed in each line connecting
the purge gas to the process panel equipment.
6.3.2 Process Gas Cylinder Contamination by Purge
Gas — The purpose of purging is to remove air or
residual process gas from the panel equipment (or part
of it) back to the internal cavity of the closed cylinder
valve.
WARNING: Check valves are not acceptable in this
part of the process gas system because purging would
be defeated. Cross contamination can only be prevented
by safeguards which assure complete cylinder valve
closure and process gas venting, before purging begins.
6.4 Materials — All materials furnished should be
manufactured to nationally recognized standards.
Metals used for the wetted surfaces should be type 3l6L
stainless steel, or other materials that provide equal or
improved compatibility with the gas in service.
Nonmetallic seals that are used in valve or regulator
seats must also be compatible with the product in
service.
6.5 Joints — All welded joints should be butt welded
(no socket welds) and should comply with SEMI F3.
Connection fittings should be face seal type.
6.6 Particle Control — Particle contamination is
controlled through the proper selection of components
and system hardware, good design practices, clean
fabrication methods, and proper operation of the
system.
6.7 Internal Volume — The internal cavities should be
configured for minimum surface area and internal
volume to enhance purging. Dead end legs should be
eliminated or kept to a minimum volume and length.
6.8 Maintainability — Planned maintenance or forced
repair is facilitated or inhibited by specific design
concepts and features. From a safety point of view, it is
mandatory to be able to purge the entire GSCE (all
cavities) and to have a downstream shutoff (low
pressure isolation valve) and disconnect fitting.
7 Performance Recommendations
7.1 Functional Recommendations
7.1.1 The ASO should be designed to close based on
an alarm or fail signal from an auxiliary component. It
should be designed to fail closed and should have a
working pressure at least 1.1 times the product cylinder
pressure. If a pressure sensor is located between the
ASO and the cylinder valve, as depicted in Figure 1, it
should also have a working pressure at least 1.1 times
the product cylinder pressure.
7.1.2 Pressure Reduction — Gases are most
commonly required at POU at less than 100 psig.
Cylinder pressure is reduced to the lower pressure by a
gas pressure regulator, when necessary.
CONNECTION
Figure 1
Typical Gas Source Control System
SEMI F13-1101 © SEMI 1993, 2001 4
7.1.3 Excess Pressure Control — Provisions should be
made to protect the distribution piping and process
equipment from excessive pressure. This protection
may include a pressure transducer, pressure switch, or
indicating transmitter connected to close the ASO, a
relief valve piped into the exhaust, or a redundant
pressure regulator with primary regulator failure
indication.
7.1.4 Cylinder Contents — The product remaining in
the cylinder is determined by gas pressure measured by
either a pressure transducer or gauge, or in the case of
material in liquid/vapor phase, by the cylinder weight
measured by a scale.
7.1.5 Delivery Pressure — The pressure delivered by
the regulator is displayed by a pressure indicator. This
can be either a gauge or transducer readout.
7.1.6 Filters — Particles from ambient sources,
entering with the product or generated by the system
elements, can be captured by including one or more
filters at a variety of locations within the system. This
practice tends to protect the components and the
process.
7.1.7 Purge Gas Connection — A purge gas
connection is provided via a branched connection to
admit clean, dry, inert purge gas through an on-off
valve. This is commonly located between the cylinder
connection and high pressure isolation valve in the
panel system. Gas purging is used for installation of a
new system, before disconnecting a spent cylinder, after
connecting a fresh cylinder, and for removal of
equipment for maintenance purposes.
7.1.8 Vent Outlets — The normal purpose of the vent
valves is to discharge process gas, air, and purge gas in
conjunction with purging operations. Under special
circumstances, they are used to reduce pressure in the
equipment and/or transfer product. One or more vents
may be used at various locations, and downstream
venting may be either atmospheric pressure or vacuum
from a venturi or pump. Vacuum venting is strongly
recommended.
7.1.9 High Pressure Indication — A pressure indicator
in common with the high pressure line connected to the
cylinder valve is required to indicate the presence of
residual process gas, or an open or leaking cylinder or
panel valve. It also shows application of adequate purge
gas pressure, and, in cases where vacuum-assisted
purging is employed, an indication of the vacuum level
should be included.
7.1.10 Cylinder Connection Makeup — After a fresh
cylinder has been connected, the integrity of the
cylinder valve connection can be tested with the use of
the pressure indicator mentioned in Section 7.1.9.
7.2 Failure Modes — Any one of a number of
conditions will require emergency action. Some are
more serious than others. In some cases, the
consequence is shutdown of the panel equipment and
venting to a properly controlled discharge system.
These failures should be addressed in the hardware and
operational design phase of the system.
7.2.1 Excessive Delivery Pressure — Due to
equipment malfunction or operator error.
7.2.2 Leaking fitting or component malfunction may
require gas detection monitor.
7.2.3 Excess Flow — This can be the result of operator
error or catastrophic conditions, such as a sheared
delivery line.
7.2.4 Cabinet exhaust failure.
7.2.5 Mechanical failure of panel equipment parts or
downstream equipment.
7.2.6 Destruction to plant through fire, explosion,
earthquake, crash, etc.
7.2.7 Inadvertent mishandling of distribution
equipment.
7.2.8 Process tool problems.
7.2.9 Control system failure.
7.2.10 System Abuse/Misuse — Source gas quality may
affect service life and operability of the system. Poor
gas product quality may cause a reduction in
performance of the system that can lead to premature
hardware component failures.
8 Acceptance Test
8.1 All gas source control equipment should undergo
an acceptance test, agreed to and understood by the
customer and supplier, before it is delivered. This test
should ensure that all control and operational functions
perform as required by the customer’s and/or supplier’s
specifications.
9 Qualification Test
9.1 GSCE should be qualified at its installed location
with an inert gas prior to installing the process gas
cylinder. This test should include the operation of all
control and hardware functions, interface with the
process tool and all interconnected safety devices,
systems, and alarms. This should also include a system
wide leak test of all possible leak points, such as fittings
and welds.
SEMI F13-1101 © SEMI 1993, 20015
10 Labeling
10.1 The GSCE panel should be labeled for the
product. Further labeling as defined in SEMI F14
should be affixed to the outside of the door of the
enclosure.
11 Instructions
11.1 The purchaser’s requirements will dictate the
information provided with the equipment. Minimum
acceptable instructions will vary with the complexity of
the equipment (e.g., manual, automatic, microprocessor
or pneumatically controlled, analog or digital, etc.) In
all cases, the following information should be included:
11.1.1 “WARNING: Read Instructions Before
Proceeding. (Instructions No. xxx for System No. xxx)
Do not proceed without understanding the status of the
equipment as received, or damage may result.”
11.1.2 Installation
11.1.2.1 Certified status of equipment as shipped
should include:
11.1.2.2 Leak integrity,
11.1.2.3 Particle level,
11.1.2.4 Contaminants,
11.1.2.5 Storage requirements,
11.1.2.6 Status indicators,
11.1.2.7 Removal of shipping safeguards,
11.1.2.8 Physical mounting and connection details, and
11.1.2.9 Purging during preparation and start-up.
11.1.3 Start-Up Method
11.1.3.1 Perform purge for initial start,
11.1.3.2 Pre-process (with substitute inert gas),
11.1.3.2.1 Confirm all component functions,
11.1.3.2.2 Confirm all operating levels and setpoints,
and
11.1.3.2.3 Confirm leak integrity.
11.1.4 Process Service — Operational purge
procedures that include the number of purge cycles and
purge pressure and vent dwell times, that take into
account the configuration of the system and the
intended process gas, should be determined before
process gas is installed.
11.1.5 Maintenance — Maintenance purge procedures
and panel repair and replacement procedures should be
defined before process gas is installed.
NOTE 3: Special warnings about the potential for dead space
in components or fittings, etc. (in normal or failed mode)
should be identified to avoid producing a hazardous condition
for any subsequent operation or handling at any location.