New Updates to Equipment Productivity and Reliability Standards -SEMI E10 and SEMI E79
By David Busing (Consultant), Steven Meyer (Intel), David L. Bouldin (Fab Consulting), Michael Tran (SEMI Standards)
In recent Cycle 2, 2014 voting, the SEMI Standards community approved simultaneous revisions to SEMI E10, Specification for Definition and Measurement of Equipment Reliability, Availability, and Maintainability (RAM) and Utilization and SEMI E79, Specification for Definition and Measurement of Equipment Productivity. SEMI E79, in particular, was well past its mandatory five-year review cycle and in need of technical and editorial updates as well as a thorough review by the user community. It was the objective of the Equipment RAMP (Reliability, Availability, Maintainability, and Productivity) Metrics Task Force (TF), that upon approval of these two letter ballots, that the Documents will be mutually consistent and sufficiently clear and complete requiring no major technical content changes until the next mandatory five-year review cycle.
A primary accomplishment of the revision to SEMI E10 is the introduction of a substantial set of example calculations as a new section, Related Information 2. This example covers a scenario for a five-module multi-path cluster tool (MPCT) with three processing equipment modules, a handler equipment module, and a mainframe equipment module organized into two intended process sets (IPSs). The scenario exercises key features of the SEMI E10 state tracking and metrics. An event-by-event description explains how equipment module events become equipment module states, how equipment modules states become IPS states, and how the IPS states become states for the MPCT. All fundamental quantities for the metrics and the metrics themselves are calculated for all equipment systems, including the individual equipment modules, the IPSs, and the MPCT.
The SEMI E10 revision added two other related information sections. Related Information 3 presents reporting conventions taken from the now inactive SEMI E58 (ARAMS) Document, including standard color codes for the SEMI E10 states and updated numerical codes and names of some SEMI E10 substates allowing interested users to access this content in SEMI E10. Related Information 4 presents guidance on where to draw productive time boundaries. This is accomplished by referencing equipment automation state models in other SEMI Standards and identifying when the SEMI E10 productive state (PRD) is active in those models.
Regarding technical changes in SEMI E10, none of the definitions of any metrics have changed and there are no new metrics, nor any metrics removed. The IPS state logic was revised slightly to make the IPS productive only when processing equipment modules are productive, making SEMI E10’s treatment of MPCTs more consistent with SEMI E79’s treatment. And through improved terminology, the Document now makes clear distinctions between the SEMI E10 states and the accumulated time in each of those states (e.g., the productive state versus productive time).
A primary accomplishment of the revision to SEMI E79 is the introduction of four new metrics under one subsection called Loss Metrics. These productivity loss metrics are:
- availability loss,
- operation loss,
- rate loss, and
- assignable quality loss.
These four metrics support the comparison of loss categories to each other using total time as a common denominator, and the values of these metrics plus OEE (overall equipment efficiency) add to 100% by definition. They are calculated using the same fundamental quantities used in the existing efficiency metrics, and present no new tracking requirements. The example calculations section, Related Information 1, has been extended to demonstrate these new metrics for a noncluster tool and for an MPCT.
Among several technical clarifications, the revision to SEMI E79 removed the term “virtual machine” previously used to describe an individual processing equipment module plus its related handling resources. Instead SEMI E10 and SEMI E79 now consistently require that productive time and theoretical productive time must include time for loading and unloading of units for all equipment systems. Also, the supplemental metric in Appendix 1 previously called Engineering OEE has been more accurately renamed as Optimized-Recipe OEE.
This simultaneous passage of revisions to both SEMI E10 and SEMI E79 has been in the works for a several years, since the two separate TFs for revising E10 (the E10 Revision TF) and E79 (the Equipment Productivity Metrics TF) were consolidated into the current Equipment RAMP Metrics TF. Having achieved this milestone, this TF is now turning its attention toward technical education of the user community and away from major technical revisions.
If you are interested in participating in the Equipment RAMP Metrics Task Force, the Metrics Global Technical Committee or would like more information on the SEMI International Standards Program, please contact SEMI at email@example.com
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SEMI, Standards Watch - June 2014