SEMI F50 - Guide for Electric Utility Voltage Sag Performance for Semiconductor Factories

Volume(s): Facilities
Language: English
Type: Single Standards Download (.pdf)

This Standard was technically approved by the Facilities Global Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on August 22, 2013. Available at and in December 2013; originally published February 2000; previously published November 2008.


NOTICE: This Document was reapproved with minor editorial changes.


This Guide provides a framework for semiconductor and flat panel display (FPD) manufacturers and their electric utility service providers to minimize the effect of voltage sag events on semiconductor processing. In particular, this Guide focuses on electric utility power quality performance goals that are complementary to voltage sag immunity levels for semiconductor processing equipment and facilities infrastructure equipment (see Figure 1). Recommendations for measuring and evaluating voltage sag performance, evaluating utility system enhancements, and implementation of a continuous improvement process are included since no electric utility industry standards exist.


Utility systems are designed, constructed, and operated to meet utility industry regulations and requirements. One important requirement for semiconductor factories is power system reliability. Utilities measure reliability in minutes of voltage outages per customer per year. Semiconductor factories require a high level of power system reliability, any service outage is usually unacceptable. A second important requirement is power quality. Power quality relates to disturbed voltage waveforms, not outages. When utilities implement measures to increase power system reliability, power quality can be adversely affected. The structured approach defined in this guide can achieve high levels of power quality without sacrificing power reliability.


The intent of this Guide is to help semiconductor manufacturers achieve both high levels of power reliability and power quality from energy utility providers. By becoming familiar with the cause and effect relationships of voltage sag events on the utility’s side of the electric meter, semiconductor manufacturers and electric utilities can work together to pursue efficient solutions for improved voltage sag ride-through in semiconductor factories.


The scope of this Guide extends beyond a discussion of typical electric utility reliability and quality improvement techniques to developing a continuous improvement process for electric utility voltage sag performance (depicted graphically in Figure 2). Factors in this process include the following:

  • Define desired performance criteria by setting goals for voltage sag event duration and magnitude (see ¶ 6.1).

  • Measure performance for both proposed and existing semiconductor factory sites (see ¶ 6.2).

  • Summarize voltage sag event data and identify the impact on semiconductor processing and facilities infrastructure equipment (see ¶ 6.3).

  • Recommend improvements that include consideration of cost, benefit, and risk. Improvements can include corrective action to eliminate system faults, changes to service configurations, and power enhancements (see ¶ 6.4).

  • Select and implement improvements. Establish a continuous improvement process (see ¶ 6.5).


For the purposes of this Document, the term Electric Utility refers to energy service providers (that sell energy to semiconductor manufacturers) and/or electric transmission and distribution providers (that deliver energy through their power lines).


Referenced SEMI Standards

SEMI S2 — Environmental, Health, and Safety Guideline for Semiconductor Manufacturing Equipment

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