Which Version of SEMI S2 Should I Use?
This question arises as equipment makers begin the process of getting their equipment evaluated for safety. Over the past 12 years, SEMI™ has published eight different versions of SEMI S2, the Safety Guideline for Semiconductor Manufacturing Equipment. SEMI S2’s inaugural publication was completed in 1991 when a core group of safety personnel representing end-users and equipment manufacturers developed a document to harmonize safety requirements among end-users. The goal was to create a common set of requirements that would eliminate the need for manufacturers to meet the “Intel Spec” and the “IBM Spec” and the “Motorola Spec” and the “AMD Spec,” etc.
Shortly work began to expand and refine the requirements in SEMI S2-91. Two years later, a new, more comprehensive document was created. SEMI S2-93 slowly gained recognition among chip makers and equipment manufacturers alike to become “the” industry standard for equipment safety requirements.
In 1996, SEMI S2-93 was updated with a Related Information section that documented an industry position on the use of SEMI S2 to show conformity with European Machinery and Low Voltage Directives. The updated version became SEMI S2-93A.
In 1997, work began to update SEMI S2 again. SEMI’s mandatory 5-year rewrite requirement was coming up, and due to its growing popularity and use, efforts began in earnest to rewrite S2. The goal with the rewrite was to expand the scope to cover more hazards, to fix the obvious shortcomings, and to integrate the concepts of risk analysis.
After nearly four years of work, a new SEMI S2 was published in February 2000. This document was a complete update of the requirements and included key changes in approach, especially with the inclusion of risk assessment and the concepts of “acceptable risk” and “conforms to the intent.” This document also included several new sections, Mechanical Design, Hazard Warning Labels, Hazardous Energy Isolation, Automated Material Handlers, and Lasers. The new document was not intended to be applied retroactively to older equipment; however, many end users were quick to add this document version to their purchase specifications. In most cases, manufacturers with equipment designed and evaluated to SEMI S2-93 were grandfathered under this process. However as time has gone on, most manufacturers have been urged to update their assessments to the new requirements. Unfortunately, many manufacturers found that their new equipment, primarily 300mm tools based on designs evaluated to SEMI S2-93A, did not meet the new requirements of SEMI S2-0200.
SEMI S2-0302 SEMI S2-0302 was published in March of 2002 and represented updates to keep, or bring into agreement, several referenced documents, most notably SEMI S14, “Safety Guideline for Fire Risk Assessment and Mitigation for Semiconductor Manufacturing Equipment.” With this significant change, fire risk assessment using SEMI S14 was required by SEMI S2.
SEMI S2-1102 & SEMI S2-0303
SEMI S2-1102 and S2-0303 followed right on the heels of ‘-0302. The updates covered in these versions were mainly editorial corrections and alignment of S2 with other SEMI “S” guidelines such as S9 and S14.
SEMI S2 had its latest update published in July 2003. This version was updated to include Related Information Section 14 and changes to Sections 11 and 12. This update permits the use of software and firmware controls under certain conditions. This is the first time that there were clear guidelines as to the use of software and firmware in safety control circuits. Previously, discrete hardware devices were required in most cases.
Additionally, SEMI S2-0703 became the version of record for the next 3 years. In the SEMICON West meetings in San Francisco in July 2003, the North American EHS Committee voted to freeze the requirements in SEMI S2 and implement the Change Management plan. See Update Semiconductor for more information. Line I\item changes to SEMI S2 that are balloted and approved by committee between July 2003 and July 2006 will be published as part of editorial changes to the document as Related Information, but they will not be mandatory requirements of the guideline until July 2006.
Which one is right for you? Well, that all depends. In most cases, your customer will let you know in the purchase documents for the system. Currently, a large percentage of equipment is simply a modified version of equipment that was previously evaluated. In these cases, due to the common shared platform or legacy systems, the new configuration could be evaluated to the same version that the old one was. For significant re-designs of systems and new equipment, SEMI S2-0703 should be used to get the most life out of the evaluation.
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