New SEMI Standards to Systematically Identify and Reduce Time Waste and Improve Cycle Time in Fabs

SEMI Publishes New Standards to Systematically Identify and Reduce Time Waste and Improve Cycle Time in Semiconductor Fabs

The SEMI Wait Time Waste Task Force in the Metrics Committee, led by SEMATECH, has approved a standard method for identifying product time waste or “Wait Time Waste” (WTW) for semiconductor equipment, to measure when the lot or wafer is waiting, or when it is active (processing, transport, inspection, or measurement). Time waste is unnecessary wait time or active time that is longer than necessary.  Consistent, systematic measure of product time enables fabs to expose hidden waste that might not otherwise be detected.  Reducing time waste can add valuable hours of production time per day – a significant cost savings of as much as $100 million for each day of cycle time.

SEMI E168, Primary Specification for Product Time Measurement in Semiconductor Manufacturing defines a method for organizing and preprocessing factory data to support the detection and reduction of product time waste for a product during its factory lifecycle. The method takes a user-specified time period, breaks it down into contiguous time segments and categorizes each time segment as a type of active or wait time. Factory events and context data are used to delineate the time segments. The output of product time measurement (PTM) is an analysis-ready dataset. Procedures for analysis of the data to identify specific product time waste are excluded from this document.

SEMI E168.1, Subordinate Specification for Product Time Measurement in Semiconductor Manufacturing in GEM 300 Production Equipment, focuses on the time wafers spend in production equipment using SEMI standard SECS/GEM events to identify the start and end of each time element. The time-stamped GEM 300 event that marks the end of one time element is the same event that marks the beginning of the next time element, ensuring there are no gaps in the data.

Standardized metrics and methods enable faster, more automated extraction of events from communication logs, and mapping of events and context data to time elements, to produce analysis-ready datasets, or PTMData.  The PTMData file can be imported into the tool of choice, including Excel, visualization and analysis.  Determining which time is “waste time” is out of the scope of the standards.

A standardized way to measure and communicate product time measurement enhances the ability of device makers and equipment suppliers to collaborate on cycle time optimization. Working together, device makers, equipment suppliers, and software solutions providers ensure that the standards serve the needs of SEMI Standards members and reflect current practices in the industry.

Future Activities

Further refinements to SEMI E168 and E168.1 for 300mm equipment are already being discussed within the Wait Time Waste Task Force with plans for letter ballot in May 2014.  Furthermore, the Wait Time Waste Task Force will next define a subordinate PTM standard for Automated Material Handling Systems (AMHS). SEMATECH is currently in the process of defining the events and time periods for AMHS used in most fabs today.  As with the equipment standards, SEMATECH plans to validate specification with factory production data prior to ballot submission. Device makers and suppliers who wish to contribute to the development and validation of the AMHS PTM standards are encouraged to join the WTW Task Force.

Get Involved

If you are interested in participating in the Wait Time Waste Task Force, the Metrics committee or would like more information on the SEMI International Standards Program, please contact SEMI at


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February 4, 2014