SEMI F47-0706 Abstract

Originally published September 1999 and Previously published February 2000, this document was completely rewritten in 2006. This document replaces SEMI F47-0200 and SEMI F42-0600.

Semiconductor factories require high levels of power quality due to the sensitivity of equipment and process controls. Semiconductor processing equipment is especially vulnerable to voltage sags. This specification defines the voltage sag immunity required for semiconductor processing, metrology, and automated test equipment. This specification strikes a balance between voltage sag immunity and increased equipment cost.

NOTE 1: The requirements and recommendations in this international specification were developed to satisfy semiconductor industry needs. While differing from other generic requirements, this industry-specific set of requirements and recommendations is not in conflict with known generic equipment regulations from other regions or generic equipment specifications from other organizations.

NOTE 2: To minimize design effort and testing, this revision aligns SEMI F47 test methods with applicable IEC standards, while retaining the previous SEMI F47 test levels. It also incorporates knowledge gained in the first five years of experience with this specification.

This specification sets minimum voltage sag immunity requirements for equipment used in the semiconductor industry. Immunity is specified in terms of voltage sag depth (in percent of nominal voltage remaining during the sag) and voltage sag duration (in cycles or seconds).

This specification also sets procurement requirements, test methods, pass/fail criteria, and test report requirements. The primary focus of this specification is semiconductor processing equipment including but not limited to the following types:

• Etch equipment (Dry & Wet)
• Film deposition equipment (CVD & PVD)
• Thermal equipment 
• Surface prep and clean equipment
• Photolithography equipment (Scanner, Stepper & Tracks)
•  Ion Implant equipment
• Metrology equipment
• Automated test equipment
• Chemical Mechanical Polishing/Planarization equipment
  

The secondary focus of this specification is subsystems and components that are used in the construction of semiconductor processing equipment, including but not limited to:

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

This specification 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.

Grandfather Clause - Equipment, subsystems, and components that were tested or certified under the previous version of this specification, prior to the publication date of this specification, do not require re-testing or re-certification until hardware or software design changes that could affect voltage sag immunity are implemented.

NOTICE: This standard does not purport to address safety issues, if any, associated with its use. It is the responsibility of the users of this standard to establish appropriate safety and health practices and determine the applicability of regulatory or other limitations prior to use.

Referenced SEMI Standards SEMI E51 - Guide for Typical Facilities Services and Termination Matrix SEMI S2 - Environmental, Health, and Safety Guideline for Semiconductor Manufacturing Equipment NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.

Why Change SEMI F47?

The original SEMI F47-0200 (voltage-sag immunity) was found to be highly successful in reducing service costs and increasing tool reliability and uptime. However, since 2000, semiconductor manufacturers, tool suppliers, and compliance-testing companies have amassed a significant technical and practical knowledgebase related to testing. This information was deemed beneficial to incorporate in a revised standard. Furthermore, since new IEC voltage-sag standards IEC 61000-4-11 and IEC 61000-4-34 have emerged, closer harmonizing between the SEMI F47 standard and these new standards was desirable.

What Did Not Change?

When considering the changes in the standard, noting what did not change is helpful. First, the goal of the revision is the same as the original SEMI F47 goal. Basically, the standard is designed to lead to semiconductor tools that are robust to voltage sags. This is to be done through strategies to design and select robust components. Furthermore, the pass/fail criteria for tools did not change. The pass/fail terminology is still based on the terminology and understanding from the original SEMI F47. With the exception of eliminating one test point, the basic test levels did not change. Finally, other terminology used in the standard is basically the same as in the original SEMI F47.

What Did Change in the New SEMI F47-0706 Standard?

One of the first things that will be noted when reviewing the revised standard is that the short-duration test point of 50 ms at 50% of nominal voltage was removed. The thought was to simplify the testing, and the revision task force came to the conclusion 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 is unnecessary. This point can be argued, and indeed test data has shown that there are sometimes exceptions to the basic assumption made by the task force. Nonetheless, 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.

One will also note that the referencing of test durations is now presented in cycles only, with specific values for test durations at 50 Hz and 60 Hz. The original test durations were based on milliseconds and seconds. The task force felt that even though the unit of seconds is the most universally understood, alignment with the IEC 61000-4-11 and 61000-4-34 standards was better served by utilizing the “cycles” unit format for duration. Furthermore, utility engineers and many in the power industry visualize AC voltage in cycles rather than in units of seconds.