Thursday, April 7, 2011

SEMI F47 is the standard for Semiconductor Equipment Voltage Sag Immunity. It was updated in 2006 to its latest version, SEMI F47-0706, which replaces the following previously published documents:

1.   SEMI F47-0200 – Specification for Semiconductor Processing Equipment Voltage Sag Immunity (Old SEMI F47 Standard published in 2000).

2.   SEMI F42-0600 - Test Method for Semiconductor Processing Equipment Voltage Sag    Immunity (Explains the method on how to test compliance with SEMI F47).

SEMI F42-0600 standard is now superceded by SEMI F47-0706 and IEC 61000-3-4 (Limitation of emission of harmonic currents in low-voltage power supply systems for equipment with rated current greater than 16 A). This is to replace the specific (step by step) approach for tool testing of SEMI F42 with a more generic test description. However, SEMI F42 can still be use as a reference. In addition, those who want to gain comprehensive understanding of how to carry out voltage sag testing shall contact industry experts for guidance.

SEMI F47 Changes and Revisions

The following statements discuss and present the summary of the changes and revisions to SEMI F47 standard:


The purpose and objective of the revision is to incorporate the collective information of significant technical and practical knowledge base related to testing from semiconductor manufacturers, compliance-testing companies and tool suppliers, since 2000. Also, another reason is to harmonize SEMI F47 standard with the new IEC voltage sag standards - IEC 61000-4-11 and IEC 61000-4-34. In short, it is to update SEMI F47.

Changes in SEMI F47

1.    The short-duration test point of 50 ms at 50% of nominal voltage was removed in SEMI F47-0706. The rationale is that if tested equipment is immune to the test point at the 200 ms and 50% of nominal, then testing at 50 ms and 50% of nominal becomes unnecessary. Subsequently, the number of test points required to conduct the test was reduced from four points to three points for each phase combination that must be evaluated.
SEMI F47-0200 Table
SEMI F47-0200 (Old SEMI F47 Standard)
SEMI F47-0706 Table
SEMI F47-0706 (Latest SEMI F47 Version)
      Note: Sag depth is expressed in percent of remaining nominal voltage. For example, during a 80% sa sag on a 200 volt nominal system, the voltage is reduced during the sag to 160 volts (not 40 volts). 

2.    Referencing of test durations is now presented in cycles only, with specific values for test durations at 50 Hz and 60 Hz, in contrast to the SEMI F47-0200 test durations that were based on milliseconds and seconds. Although the unit of seconds is the most universally understood, alignment with IEC 61000-4-11 and 61000-4-34 standards was better served by utilizing the cycles unit format for duration. Likewise, utility engineers and many in the power industry visualize AC voltage in cycles rather than in units of seconds.
3.      Equipment must now pass at the test point levels rather than “above the defined line”
4.  Compliance with the new SEMI F47-0706 is defined by passing three test points rather than compliance to a “Curve” as defined in SEMI F47-0200. Use of Implied Curve is still valid for comparing against Power Quality Data.
5.     Test Vectors are defined, wherein SEMI F47-0200 this information is only implied.
Ø  Single-Phase Test Vectors are the Same
Ø  Three Methods of Allowable Phase-to-Phase Test Vectors are allowed

6.    Pass/Fail Criteria is broken out now for Tooling Equipment and Subsystems
Ø  Tooling equipment still use the Interrupt Criteria
Ø  Subsystems have Three Classes of Responses

7.    Specific Requirements of Certification Documents are now defined.
8.    A Significant Related Information Section assists the reader in a comprehensive understanding of the intent.
9.  Section addressing how to use the specification for procurement of tools, subsystems and components that are compliant to SEMI F47-0706 was added.
10.  SEMI F47-0706 specifically states that three-phase sags are not required.

Nonetheless, amidst these changes, the objective remains the same, which is to lead into semiconductor tools that are robust or immune to voltage sags by component selection and design strategies. In addition, the basic test levels (except for the 50 ms test point) and the terminologies used are practically unchanged.


Thomas, C. (2006). Overview of SEMI F47-0706. Tennessee: Semicon
Electric Power Research Institute. (2011). SEMI F47-0706 Abstract

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About Me

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I am an Electrical Engineer with a Masters Degree in Business Administration. My interest is in Power Quality, Diagnostic Testing and Protective Relaying. I have been working in an electric distribution utility for more than a decade. I handle PQ studies, power system analysis, diagnostic testing, protective relaying and capital budgeting for company projects.