semi合集-English.pdf - 第4026页
SEMI F50-0200 © SEMI 2000 4 that fall into different magnitude-duration cate gories. Data from di ff ere nt categori es should be adjusted by weighting factors to enable valid comparison . See IEEE 1346 fo r suggested vo…
SEMI F50-0200 © SEMI 20003
3 Limitations
3.1 This guide addresses electric utility power quality
monitoring and enhancement techniques primarily
related to semiconductor factory energy utility
providers. Process equipment and factory systems are
covered in other related standards.
3.2 This standard is not intended to address design or
materials issues related to safety which are addressed
elsewhere in the SEMI guidelines (see SEMI S2).
3.3 This document is not intended to supersede
international, national or local codes, regulations and
laws. Each should be consulted to ensure that the
equipment meets regulatory requirements in each
location.
4 Referenced Standards
4.1 SEMI Standards
SEMI S2 — Environmental, Health, and Safety
Guideline for Semiconductor Manufacturing Equipment
4.2 IEEE Standards
1
IEEE 1159 — IEEE Recommended Practice for
Monitoring Electric Power Quality
IEEE 1250 — IEEE Guide for Service to Equipment
Sensitive to Momentary Voltage Disturbances
IEEE 1346 — IEEE Recommended Practice for
Evaluating Electric Power System Compatibility with
Electronic Process Equipment
NOTE 1: As listed or revised, all documents cited shall be the
latest publications of adopted standards.
5 Terminology
5.1 electric utility — the company identified as the
contractual provider of electrical power and energy to
the customer point of delivery. Also known as the
electric service provider.
5.2 voltage sag — an rms reduction in the ac voltage
at power frequency for durations from half-cycle to a
few seconds (see IEEE 1250). Also known as voltage
dip.
6 Electric Utility Voltage Sag Performance
Recommendations
6.1 Define Voltage Sag Performance
6.1.1 Defining a goal for acceptable voltage sag
duration and magnitude is useful in establishing a
benchmark or reference point for monitoring
1 The Institute of Electrical and Electronic Engineers, Inc., 345 East
47th Street, New York, NY 10017-2394, USA
improvement. Events can be identified and categorized
within the realm of the electric utility or the
semiconductor manufacturer. Industry specifications
for semiconductor processing equipment voltage sag
immunity (which define the level of voltage sag
immunity required for semiconductor processing
equipment) are recommended as a performance goal.
Using this goal for the performance of electric utility
services will provide consistency with semiconductor
processing equipment capabilities. (See Related
Documents section.)
6.1.2 The goal for the maximum number of deviations
from specified performance per year is zero. However,
it is useful to recognize that utility generation,
transmission, and distribution systems are subject to
environmental and regulatory conditions that may
negatively influence the ability to provide zero
deviations on a continuous basis.
6.1.2.1 Document regulatory and environmental
requirements that will limit the electric utility’s choices
when implementing improvements, such as rate
structures or rights-of-way.
6.2 Measure Performance
6.2.1 Measuring Performance at Proposed Semi-
conductor Factory Sites
6.2.1.1 Factory site selection teams should consider
the importance of power and power quality when
evaluating potential sites. To insure that power quality
considerations are properly factored into the site
selection process, a selection factor should be assigned
to power quality and reliability criteria.
6.2.1.2 Utility electrical service configurations should
be considered when measuring and comparing
reliability and power quality performance at different
locations. The load profile for the proposed factory is
used to determine the standard utility electrical service
configuration. Usually, larger factories (> 10 MW)
exceed allowable loading for lower voltage distribution
systems (< 69 kV), therefore a high voltage service is
the typical configuration for larger semiconductor
factories. Selection of the highest available service
voltage is preferred for reliability due to two factors.
First, the area of exposure is greater for lower voltages
since they include both higher and lower voltage system
distribution lines and equipment. Second, higher
voltage systems can provide energy to lower voltage
system faults with little or no impact to high voltage
system voltages, whereas, lower voltage systems are
greatly impacted by faults not buffered by transformers.
6.2.1.3 The preferred method for comparing power
quality and reliability from different locations involves
creating a summary of the number of voltage sag events
SEMI F50-0200 © SEMI 2000 4
that fall into different magnitude-duration categories.
Data from different categories should be adjusted by
weighting factors to enable valid comparison. See
IEEE 1346 for suggested voltage sag event category
and weighting factors.
6.2.1.4 Model events.
6.2.1.4.1 If actual disturbance data is not available,
modeling results based on simulation of actual
electrical faults should be calculated and reviewed.
These studies called area of vulnerability analysis
determine transmission lines and equipment where
faults can adversely impact a semiconductor factory.
NOTE 2: As monitoring data is later collected, the modeling
results should be validated.
6.2.1.5 Monitor events near proposed site(s).
6.2.1.5.1 Define monitoring protocol per the method
outlined in Section 6.2.2.2.
6.2.1.5.2 Upon establishing an appropriate electrical
service configuration, reliability and power quality
information relative to that service configuration should
be requested from the electric utility. Depending upon
utility rate structures, semiconductor manufacturers
may be required to pay separately for this analysis.
Where available, the information provided should
include actual disturbance data from other selected sites
collected in accordance with IEEE 1159. Strive for
data on sites that have similar electrical service
configurations and are located electrically close to the
proposed site (e.g., ideally, from the same transmission
or distribution line).
6.2.2 Measuring Performance at Existing Semi-
conductor Factory Sites
6.2.2.1 Preparation for monitoring.
6.2.2.1.1 Review existing industry typical voltage sag
performance data for utility point-of-service.
6.2.2.1.2 Review existing site voltage sag performance
data, usually taken at a variety of locations within the
factory.
6.2.2.1.3 Review existing utility voltage sag
performance data for the area around the factory site,
usually a 20−30 mile radius of the service area is
sufficient.
6.2.2.1.4 Review existing utility area of vulnerability
modeling studies for power flow and system power
quality.
6.2.2.1.5 Document the existing utility and
manufacturing site electrical design and operating
procedures.
6.2.2.2 Define the monitoring protocol.
6.2.2.2.1 Define where measurement devices will be
located, how many to be installed, who will operate and
maintain them, and what are the standards for
calibration.
6.2.2.2.2 Define sensitivity settings. Usually
magnitude triggers are set as tightly as possible (95% of
nominal voltage). This will generate a large amount of
data that will verify trends and maximize comparison
opportunities between cause and effect. After several
evaluation cycles magnitude triggers can be moved
closer to the criteria (90% of nominal voltage), in order
to focus improvement efforts on the more significant
sags.
6.2.2.3 Monitor the voltage sag performance.
6.2.2.3.1 Location of monitor(s) should be such that
the utility point-of-service to the factory is represented
by the recorded data. Data recorded remote from the
utility point-of-service will be effected by other utility
or factory system components. Remote data should be
adjusted to represent a utility point-of-service
equivalent.
6.2.2.4 Track and report events.
6.2.2.4.1 Define the reporting format for all events and
who will receive the reports. (Example: Reports to
contain magnitude, duration, time/date stamp and
impact on process, if known. All events are
summarized and reported monthly. All out-of-
specification events only are reported same day as
event. All reports distributed to both factory and utility
representatives.)
6.3 Summarize Data and Evaluate Impact
6.3.1 Summarizing monitoring data.
6.3.1.1 Figure 3 shows how monitoring data can be
graphically reported using charts representing
magnitude and duration.
6.3.1.2 Monitored and measuring power quality
performance provides the semiconductor manufacturer
and their electric utility with empirical data on which to
base voltage sag performance and improvement
decisions.
SEMI F50-0200 © SEMI 20005
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
110%
1 10 100 1000
Duration (cycles)
Percent of Nominal Voltage
Figure 3
Example of Chart Summarizing
Monitoring Data
6.3.2 Correlate data to impact on factory.
6.3.2.1 For new sites, categorize voltage sag events
within magnitude/duration bins.
6.3.2.2 When evaluating new sites that are located in
different electrical utility service areas it is beneficial to
normalize the voltage sag data prior to comparison.
The use of magnitude/duration bins to place historical
or predicted event data creates discrete blocks of like
kind events. The impact on factories, causes of events,
and potential improvements may be evaluated on each
individual bin or groups of bins. Increasing the number
of magnitude/duration bins used in the data comparison
refines the accuracy, but also increases the effort
needed to translate events into discrete data bins. (See
IEEE 1346 and Related Information 2.)
6.3.2.3 For existing sites, define categories of event
impact on manufacturing process. For example:
• In Spec Event/No known impact
• In Spec Event/Minor impact
• In Spec Event/Major impact
• Out of Spec Event/No known impact
• Out of Spec Event/Minor impact
• Out of Spec Event/Major impact
6.3.2.3.1 The boundary between major and minor
impact is often cost or number of wafer moves lost
converted to an equivalent cost.
6.4 Recommend Improvements
6.4.1 Analyze costs, benefits, and risks.
6.4.1.1 The improvement recommendation process
should include the equivalent of identifying the costs
related to the disturbances, the costs related to
improvements, and the effectiveness of improvements.
The risks should be identified for taking no action, the
possibility that events will occur during the
implementation of improvements, and that events will
occur as a result of unknown factors resulting from the
installation of improvements. Improvements can
include corrective action to eliminate system faults,
changes to service configurations, and power
enhancements.
6.4.2 Corrective action to eliminate system faults.
6.4.2.1 The key to influencing an electric utility’s
voltage sag performance is mutual understanding of
measurement and improvement processes. Voltage
sags on utility electric systems are created because of
faults (short circuits) caused by a variety of events,
including lightning, trees contacting power lines,
equipment failure, and vehicles striking power poles.
In order to reduce the number of voltage sag events, it
is important to understand the specific cause of each
fault. Semiconductor manufacturers should request that
electric utilities share disturbance investigation reports
and statistics. If data is not available, or tracking fault
causes is not a focus (many utilities track only outage
causes) then a fault tracking system should be
established.
6.4.2.2 Many times, the initially identified fault cause
(for example lightning) has a more specific cause (for
example a contaminated insulator), with an even more
specific root cause (for example salt contamination on
coastal power lines in dry weather seasons).
Identifying this root cause helps to establish the
appropriate corrective action (for example, improved
insulator cleaning practices to include weather
considerations on coastal lines). Semiconductor
manufacturers and their electric utilities should work
together to ensure voltage sag event root cause
identification processes exists.
6.4.2.3 Analysis steps for electric utilities to identify
the root cause of system faults include the following:
Step 1 Locate the fault and identify what initiated the
fault.
Step 2 Investigate the underlying causes of the fault
to discover the root cause.
Step 3 Track faults and root causes in a database.
Step 4 Identify corrective actions.
6.4.2.4 Some of the more obvious corrective actions
include additional animal guards on exposed electrical
devices to reduce the effects from inadvertent touch.
Additional patrols and early removal of birds nests,
sources of nesting material, reduction in potential
roosting and nesting sites, sealing any possible entry to
electrical equipment against wildlife intrusion, and
designs using larger phase spacing and higher Basic