semi合集-English.pdf - 第7028页

SEMI S14-0704 © SEMI 2000, 2004 7 • li miting their energy, and • separating them from co mbusti ble mate rials of construction a nd from flammable and combusti b le process chemical s. Separation m ay be by distance or …

100%1 / 7923
SEMI S14-0704 © SEMI 2000, 2004 6
Appendix 1 should be included. For each identified
residual risk, the report should:
• explain the mechanism of loss or damage;
• identify aggravating or necessary contributing
factors;
• identify the mitigating factors;
• state the assigned Severity for each type of loss and
present the rationale for its assignment. A “type”
is a column in Table A1-1, e.g., “Equipment
Physical Damage”;
• state the assigned Likelihood and present the
rationale for its assignment; and
• state the resulting Risk category.
NOTE 18: Criteria for risks may be found in Appendix 1,
Sections A1-2.5 through A1-2.8.
6.5.3.2 This report should also describe the fire risk
mitigation techniques included in the equipment design.
6.5.3.3 The final fire risk assessment report should be
prepared or reviewed by a party qualified, as described
in SEMI S7, to do such work.
NOTE 19: This party may be an employee of the equipment
supplier or may be a third party.
6.5.3.4 When this guideline is being used as part of a
SEMI S2 equipment evaluation, the manufacturer
should make the final fire risk assessment report avail-
able to the party performing the SEMI S2 evaluation.
6.5.3.5 The equipment supplier may make the final fire
risk assessment report available to other parties.
6.5.4 Summary Report
6.5.4.1 The summary report should be prepared from
the final fire risk assessment report and contain:
• a list of the residual fire risks and their ratings, and
• brief descriptions of the fire risk mitigation
techniques included in the equipment.
6.5.4.2 The equipment supplier should provide the
summary report to users of the equipment and may
provide it to other parties.
7 Fire Risk Mitigation
7.1 Overview
7.1.1 This section describes several means of
mitigating the risks of fire. It describes ways in which
the equipment and its use can be designed to minimize
the risks.
NOTE 20: The description of a mitigation technique in this
section is not intended to imply that such technique should be
used for each system. Therefore, the decision to include a
particular mitigation technique should be based on the
assessed risk.
NOTE 21: Fire detection and suppression are also means of
mitigating fire risk. The criteria for fire detection and
suppression systems are in SEMI S2.
7.1.2 In mitigating risks, the general hierarchy of
elimination, engineering controls, administrative
controls, warning and work practices should be
followed. Following this hierarchy comprises using
techniques which are highest in it if several techniques
are equally applicable. Design and use constraints, as
well as relative cost, however, may justify using
techniques from generally less preferable categories. In
any case, the residual risk should be assessed and
reported.
7.2 Fuels
7.2.1 Materials of Construction
7.2.1.1 The lowest fire risk is posed by noncombustible
materials of construction. Available noncombustible
materials are not, however, suitable or desirable for all
applications within semiconductor manufacturing
equipment.
NOTE 22: The properties necessary to perform the intended
function of system components and the properties necessary
to satisfy component-level standards may also restrict the use
of noncombustible materials.
7.2.1.2 When materials which are combustible are
chosen, the fire risk may be mitigated by:
• selecting those materials with the least undesirable
properties as described above; and
• minimizing the total mass and distribution of such
materials.
7.2.2 Process Chemicals
7.2.2.1 It may be possible to reduce the fire risk by
changing the quantities and species of the chemicals
used in the intended processes.
7.2.3 The fire risks of combustible materials of
construction and flammable and combustible process
chemicals may also be reduced by limiting those factors
described in Section 6.
7.3 Sources of Ignition
7.3.1 Potential sources of ignition should be considered
in conjunction with the fuels and oxidizers they might
ignite.
7.3.2 Risks due to sources of ignition can be mitigated
by:
• limiting their number,
SEMI S14-0704 © SEMI 2000, 2004 7
• limiting their energy, and
• separating them from combustible materials of
construction and from flammable and combustible
process chemicals. Separation may be by distance
or by barriers.
7.3.3 Equipment in which flammable liquids or gases
are used should be assessed to determine if additional
precautions (e.g., purging) in the electrical design are
necessary.
NOTE 23: NFPA 497 and EN 1127-1 are among the
documents that provide methods for making this assessment.
7.4 Oxidizers
7.4.1 Reducing the quantities or pressures of oxidizing
process chemicals may reduce the fire risk.
7.4.2 The fire risks of oxidizing process chemicals may
also be reduced by limiting those factors described in
Section 6.
7.5 Exhaust, Enclosures and Barriers
7.5.1 Mechanical exhaust may reduce the risk of
damage to the facility, other equipment, or other
portions of the same equipment by limiting the spread
of combustion and decomposition products. The
mechanical exhaust could be provided by the
equipment or by the facility.
7.5.2 Enclosures and barriers within the equipment
may reduce the fire risk by separating the fuels and
oxidizers from each other and from potential sources of
ignition.
7.5.3 These design features may also limit the spread
of fire, reducing both the loss of equipment and the
emission of combustion and decomposition products.
8 Related Documents
8.1 SEMI Standard
SEMI S11 — Environmental, Safety, and Health
Guidelines for Semiconductor Manufacturing Equip-
ment Minienvironments
8.2 NFPA Documents
National Fire Protection Association: NFPA 70 —
National Electric Code (NEC)
National Fire Protection Association: NFPA 318 —
Standard for Protection of Cleanrooms
National Fire Protection Association: NFPA 496 —
Standard for Purged and Pressurized Enclosures for
Electrical Equipment
National Fire Protection Association: NFPA 497 —
Recommended Practice for the Classification of
Flammable Liquids, Gases, or Vapors and of
Hazardous (Classified) Locations for Electrical
Installations in Chemical Process Areas
8.3 CEN/CENELEC Standards
4
EN 1127-1 — Explosive Atmosphere – Explosion
prevention and protection – Part 1 Basic concepts and
methodology
8.4 Other Documents
Building Officials and Code Administrators (BOCA)
5
,
NBC: National Building Code
Factory Mutual System Data Sheet 7-7
6
, Semiconductor
Fabrication Facilities
International Conference of Building Officials (ICBO)
7
,
UBC: Uniform Building Code
International Fire Code Institute
8
, UFC: Uniform Fire
Code
International SEMATECH
9
, Process Compatibility
Parameters for Wet Bench Plastic Materials
(Technology Transfer # 98123623A)
Southern Building Code Congress International
(SBCCI)
10
, SBC: Standard Building: Code
4 European Committee for Standardization (CEN)/European
Committee for Electrotechnical Standardization (CENELEC), Central
Secretariat: rue de Stassart 35, B-1050 Brussels Belgium
5 Building Officials & Code Administrators International, Inc., 4051
West Flossmoor Road, Country Club Hills, IL 60477
6 Factory Mutual, 1301 Atwood Ave. P.O. Box 7500 Johnston R.I.
02919, website: www.fmglobal.com
7 ICBO, 5360 South Workman Mill Rd., Whittier, CA 90601
8 International Fire Code Institute, 5360 South Workman Mill Rd.,
Whittier, CA 90601
9 SEMATECH, 2706 Montopolis Drive, Austin, TX, website:
www.sematech.org
10 SBCCI, 900 Montclair Rd, Birmingham, AL 35213-1206
SEMI S14-0704 © SEMI 2000, 2004 8
APPENDIX 1
RISK ASSESSMENT CRITERIA
NOTICE: The material in this appendix is an official part of SEMI S14 and was approved by full letter ballot procedures on
September 3, 1999 by the North American Regional Standards Committee.
A1-1 The risk assessment should be performed for each identified fire hazard using the method provided in SEMI
S10 and the following definitions of Likelihood and Severity Groupings and Risk Categories.
NOTE A1-1: Unlike SEMI S10, in which the tables are provided only as examples, this document defines the Severity,
Likelihood, and Risk to be used herein.
A1-2 Severity
A1-2.1 The Severity Groupings are given in Table A1-1.
Table A1-1 Severity Groupings
Severity Group
Equipment Physical
Damage
Equipment Loss
of Use
Facility Loss of
Use (Minimum
Times)
Environmental and Real Property
Contamination
1 Catastrophic Loss of entire piece of
equipment
One year One week Lasting facility or environmental
impact
2 Severe Loss of major
subsystem
One month One day Temporary facility or environmental
impact
3 Moderate Loss of minor
subsystem
One week One shift Limited to the equipment, but
requiring more than routine cleanup
4 Minor Non-serious
equipment loss
One day Less than one
shift
Requiring routine cleanup but not
external reporting
A1-2.2 The Severity should be assigned for each of the columns for which information is available.
A1-2.3 The most severe Group assigned should be used in determining the risk.
A1-2.4 Each of the Severities should be reported.
A1-2.5 Contamination is by release of materials that were used in the equipment or by combustion or thermal
degradation byproducts.
A1-2.6 To be included in the assessment, a foreseen occurrence must be unplanned and include a loss.
A1-2.7 Losses exclude the performance of the design function of protective devices, such as fuses.
A1-2.8 The scope of the assessment in this document is limited to the consequences of fire.
A1-2.9 The Equipment Loss of Use time is the downtime, as defined in SEMI E10, resulting from the fire incident.
A1-3 Likelihood
A1-3.1 The Likelihood Groupings are given in Table A1-2.
Table A1-2 Likelihood Groupings
Likelihood Group Expected Frequency (% of Systems per Year)
A Frequent More than 1%
B Likely More than 0.2% but not more than 1%
C Possible More than 0.04%, but not more than 0.2%
D Rare More than 0.02%, but not more than 0.04%
E Unlikely Not more than 0.02%