Tuesday, April 5, 2011

SEMI F47 was developed by the Semiconductor Equipment Materials International. It specifies the required voltage sag tolerance for semiconductor processing, metrology, and automated test equipment. The standard aims to strike a balance between voltage sag immunity and increased equipment cost. SEMI F47 is important because semiconductor plants require high levels of power quality due to the sensitivity of equipment and process controls, especially semiconductor processing equipment, which is susceptible to voltage sags.

SEMI F47 sets minimum voltage sag immunity requirements for equipment used in the semiconductor industry, whereby immunity is specified in terms of voltage sag depth (in percent of nominal voltage remaining during the sag) and voltage sag duration. Also, it sets procurement requirements, test methods, pass or fail criteria and test report requirements.

The latest revision of the standard is SEMI F47-0706 published in 2006.

SEMI F47-0706 replaces the following previously circulated 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).

Scope of SEMI F47 

The main scope of SEMI F47 is the semiconductor processing equipment, which includes, but not limited to the following types:

Ø  Film deposition equipment (CVD & PVD)
Ø  Etch equipment (Dry & Wet)
Ø  Thermal equipment 
Ø  Surface prep and clean equipment
Ø  Ion Implant equipment
Ø  Photolithography equipment (Scanners)
Ø  Metrology equipment
Ø  Chemical Mechanical Polishing/Planarization equipment
Ø  Automated test equipment
The secondary focus of SEMI F47 is subsystems and components that are used in the construction of semiconductor processing equipment:

Ø  Radio frequency generators and matching networks
Ø  Ultrasonic generators
Ø  Power supplies
Ø  Computers and communication systems
Ø  AC Contactor coils and AC relay coils
Ø  Robots and factory interfaces
Ø  Adjustable speed drives
Ø  Chillers and cryo pumps
Ø  Pumps and blowers

SEMI F47 applies to semiconductor processing equipment to include the equipment mainframe and all subsystems whose electrical power is directly affected by the operation of the equipment’s EMO (emergency off) system.

SEMI F47 Basic Test Levels

SEMI F47 requires that semiconductor processing equipment tolerate voltage sags connected to their AC power line. They must tolerate sags to 50% of equipment nominal voltage for duration of up to 200 ms, sags to 70% for up to 0.5 seconds and sags to 80% for up to 1.0 second.
Table for SEMI F47-0706 Required Voltage Sag Immunity
SEMI F47-0706. Required Voltage Sag Immunity

A visualization of SEMI F47-0706 below depicts the required voltage sag ride-through capability curve in which semiconductor processing, metrology, and automated test equipment must be designed and built to conform. The equipment must be able to continuously operate without interruption during conditions identified in the area above the defined solid red line.

SEMI F47-0706
SEMI F47-0706
There are additional thresholds recommended by SEMI F47 but are not requirements of the standard. These include that equipment tolerate sags to 0% for 1.0 cycle and sags to 80% for 10 seconds - 600 cycles (60 Hz) and 500 cycles (50 Hz).

Table for Recommended Test Points for SEMI F47-0706
SEMI F47-0706 - Recommended Voltage Sag Immunity

Recommended Test Points for SEMI F47-0706
Graphical View of SEMI F47-0706 Recommended Test Points

Furthermore, a comparison of the different power acceptability curve as applied to certain industries is shown below.

Comparison of SEMI F47 to other Power Acceptability Curves
SEMI F47 As Compared To Other Power Acceptability Curves


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

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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.