Download Signature Journal - Power Quality Solutions for SSMC Singapore

2005
Power Quality
Solutions for
SSMC Singapore
By Er. Yong Seow Kin, Er. Soo
Mon Chuan, SSMC; Er. Chua Kok
Yong, SP PowerGrid Ltd.; Mark
Stephens, EPRI Solutions, Inc.
Systems on Silicon Manufacturing Company Pte. Ltd.
(SSMC) is a 200-mm semiconductor wafer fabrication plant
in Singapore operating as a
venture between partners
Philips Semiconductors, TSMC
Singapore, and Singapore’s
Economic Development Board
Investment.
As a high-tech wafer plant with
a capacity of 30,000 silicon
wafers per month, any power
quality issue would have significant financial impact on the
plant’s business. In this paper,
the authors share the SSMC
experience in the successful
implementation of power quality solutions (PQS) to mitigate
the impact of PQ phenomena.
Power quality landscape in
Singapore
The transmission and distribution
(T&D)
network
in
Singapore, managed by SP
PowerGrid Ltd., is a fully
underground cable system.
Though the network is spared
from environmental disturbances like thunderstorms and
other adverse weather conditions that can cause voltage
dips affecting voltage-sensitive
equipment in the plant, disturbance phenomena exist in the
network as in any other power
systems. Voltage dip incidents
in the network are mainly due
to equipment and cable faults
in the network, equipment
faults at customer installations, and cable damage by
earthworks carried out by a
third party.
SP PowerGrid has adopted a
two-prong strategy of prevention and containment in managing power quality in
Singapore. The initiatives to
minimize the frequency of voltage dips include:
• Network enhancement
via electrical splitting of
supply blocks to significantly reduce the severity
of dips experienced by
customers,
• Condition monitoring of
equipment to detect incipient faults before they
develop into failures leading to voltage dip,
PQ Singapore: Continued on p. 2
Silicon Manufacturing Company Pte. Ltd. (SSMC) in Singapore
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PQ Singapore: Continued from p. 1
• Cable damage prevention
efforts, and
• Power quality monitoring
system to characterize the
network for benchmarking
and improvements. The
information is also made
available to customers for
evaluation of their equipment voltage sensitivity
threshold and hardening
measures.
In partnership with end-use
customers, SP PowerGrid provides information about the
performance of the supply system so that customers can
make informed decisions on
measures to take in hardening
their plants against the impact
of voltage dips on sensitive
equipment. Besides publishing
details of network performance
on its website, SP PowerGrid
also carries out joint investigation and testing of customers’
equipment sensitivity, recommending mitigation solutions
to customers for their consideration, and conducts technical
workshops to share with customers power equipment
maintenance experiences, etc.
SP PowerGrid has also proactively initiated more outreach
and interaction with:
• A power quality advisory
panel to consult and tap
ideas from industries, promoting collaboration and
sharing of experiences;
• Power quality interest
groups as a platform for
regular meetings and
exchange of experiences
and to address specific
concerns
of
interest
groups;
• Customer managers program serving customers
across industries for regu-
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lar updates and operational
liaison; and
• Power quality forums and
workshops to share experiences with industries;
and
• A power quality guidebook. The guidebook is a
consolidation of experiences and understanding
of power quality, gathered
from working in close partnership with customers
over the years.
The need for PQ solutions
at SSMC
When SSMC Singapore started
ramping up wafer production in
2000–2001, the company experienced a number of voltage
dips causing sensitive production tools and facilities systems
to trip, resulting in product and
equipment damage, scrap, production downtime, as well as
lost labor in recovery and
restoration. The company
decided it was necessary to
mitigate the impact of the voltage dips using the PQS program. The program comprises
six basic steps:
1. Assess the impact (financial, etc.) of the PQ problem on production and
facilities.
2. Understand contributing
weak links in facility tools
and systems.
3. Study the various PQS
options available to mitigate the problem.
4. Formulate an investment
and implementation plan.
5. Implement the plan and
review effectiveness.
6. Adjust the implementation
plan based on the results.
In applying the PQS process to
SSMC, the critical success factors identified were:
• Understanding the financial impact of any voltage
dip event to SSMC;
• Identifying the weak links
within tools and facilities
systems through a PQ
audit;
• Evaluating the various PQ
solutions, and choosing
the most cost-effective;
• Formulating an investment
and implementation plan
with business conditions
in mind;
• Implementing and reviewing the effectiveness of
PQS; and
• Fine-tuning the implementation plan if necessary.
For successful implementation,
management must be willing
to commit adequate funds and
in-house resources. Participation by related vendors is
also crucial, especially when
complicated systems and tools
are involved. Good teamwork is
of paramount importance.
Understanding financial
impact
In order to assess the financial
impact of voltage dips, SSMC
put in place a systematic datagathering process to gather
details of voltage dip events
and consequential impact to
SSMC. Additional information
provided by SP PowerGrid from
their monitoring system included details on voltage dip incidents with date, time, magnitude, duration, and root causes
of dip.
As demonstrated in the figure
below, this process determined
that there were a total of 14
voltage dip events in 2000 and
2001, and that 6 of these fell
below the thresholds established in the SEMI F47 standard and were very likely to
cause process interruptions.
Evaluating PQS mitigation,
investment, and implementation options
Having identified the types and
severity of voltage dip events,
the PQS process turned to
examining the range of mitigation options available, including:
1. Incoming of entire plant
(most expensive, but least
complex),
SSMC power dip records for the years 2000 and 2001
2. Switchboard- and distribution-panel level (or group
of tools),
Simulated impact of a dynamic sag corrector on control voltage for a chiller
3. Incoming power to each
individual tool, and
4. Individual
components
within tool or equipment
(cheapest,
but
most
detailed and complex).
The challenge is to optimize the
selection of mitigation so as to
offer the best return on investment to the company. This
means investing just enough to
ensure the value of production
impact mitigated by the PQS
implementation justifies the
amount of investment. At
SSMC, a prioritized list of the
most important (and most vulnerable) processes was developed. For example, the prioritized list in the table at right
was developed for mitigation of
impact on wafer production
tools.
Implementation and review for production tools and facilities chiller systems
Batch processing tools with high potential of wafer scrap, exceeding 25 wafers.
High Priority
Production
Tools
A good example of the implementation of the PQS process
can be found in the critical facilities systems within SSMC.
Many of these were already
designed with battery-based
uninterruptible power supplies
(UPSs), including the plant’s
facilities monitoring and control
system, life safety system, and
some of the process exhaust
fans and process cooling water
(PCW) pumps. In addition,
although a significant number
of variable speed drives (VSDs)
were widely used for processrelated pumps and fans, many
of these VSDs were able to ride
through numerous voltage dip
events without impact due to
use of a “flying” restart feature.
Single wafer processing bottleneck tools with long recovery time, > 8 hours.
Support or metrology tools needed for main tool recovery.
Medium
Priority
Low Priority
High potential of wafer re-work.
Potential wafer scrap exceeding 5 wafers.
No impact, short cycle time, low repair damage, cost, etc.
Facility Chiller
Systems
Potential plantwide production interruption or impact to quality.
Obviously, much of the plant’s
critical facility equipment was
already “hardened” against the
vagaries of voltage dips.
High Priority
High repair costs.
Medium
Priority
Low Priority
Potential localized or partial interruption to production.
Moderate repair costs.
No impact, short cycle time, low repair damage, cost, etc.
PQ Singapore: Continued on p. 4
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PQ Singapore: Continued from p. 3
However, many of the facility’s
HVAC chillers were found to be
affected by the voltage dips,
and as a result, clean-room,
ultra pure water, and PCW systems were impacted. The PQS
team therefore found it attractive to implement PQS for the
chillers, incorporating a dynamic sag corrector on the secondary side of the chiller’s control
power transformer.
With the assistance of SP
PowerGrid, the PQS team conducted vigorous simulation
tests to determine the effectiveness of the solution. The
results were very successful—
the chillers rode through all
subsequent voltage dips, as
illustrated in the figure on the
previous page.
Subsequent application of the
PQS process to production
tools was also successful,
including mitigation with dipproof inverters and additional
dynamic sag correctors. Based
on this success, SSMC is in the
process of implementing further PQS processes elsewhere
in its facility.
Acknowledgments
The authors wish to thank
SSMC Management for permission to use the PQS reports
for publication in this Signature
Journal, vendors and PQS
device suppliers who have supported and been working with
SSMC, PQS consultant EPRI
Solutions for their sharing of
knowledge on PQS, SP
PowerGrid for various assistance in testing for SSMC, and
all other parties who have contributed in one way or another
to make this learning and sharing possible.
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Signature Journal is a publication of EPRI Solutions’ Power
Quality Knowledge-Based Services (Program 97).
EPRI Solutions Program Director
Bill Howe, PE, Director of Technology Information Businesses,
EPRI Solutions, Incorporated
Production
Nanette Jones, Graphic Designer, EPRI Solutions, Inc.
Letters to the editor may be sent to Bill Howe at the EPRI
Solutions, Inc., e-mail [email protected]. For subscription information contact the EPRI Customer Assistance Center
at (800) 313-3774 or [email protected]. Subscriptions are free to
EPRI Power Quality funders, $195/year to other EPRI members,
and $395 to non-EPRI members. Signature Journal is available to
Program 97 subscribers online at www.MyPQ.net.
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