By Al Brown
As a consultant conducting SEMI S14 fire risk assessments since its introduction in 2000, readers would expect me to actively promote the application of fire risk assessment to semiconductor equipment manufacturers. Three years since its inception, however, I've found that there are clear benefits to undertaking the process and producing reports for end users as well.
Since SEMI issued S14—the safety guideline for fire risk assessment and mitigation of semiconductor manufacturing equipment—manufacturers of steppers, single-wafer processors and batch wet process tools, lasers, MOCVD reactors and ion implanters have asked specialists to assess their equipment. Some make the request because it's required for compliance to SEMI S2, while others are required to complete an assessment by the end-user.
Some end-users have even commissioned S14-style assessments of existing production machines to help prioritize risk mitigation programs and facilitate meaningful discussions with the Authority Having Jurisdiction (AHJ).
At an Environmental Health and Saftety Interest Group meeting at SEMICON West in San Francisco, Texas Instruments' (TI) Craig Ottesen explained how TI used S14 reports to help manage fire risks, and how those reports became an integral part of the risk management process—particularly for 300-mm production equipment purchased for DMOS 6.
Demonstrating the value of S14 reports to the end user, Ottesen highlighted the fact that well-executed SEMI S14 reports clearly identify fire risks inherent in production equipment. When evaluated in conjunction with the fire-safety options available to the purchaser, the safety manager can quickly confirm whether the correct fire safety features have been ordered, or can identify outstanding fire risk issues that may need to be discussed with insurers or AHJs.
A well-written S14 report can provide a wealth of information to the end user. But the value can be increased when accompanied by a compliance report covering standards such as FM 7-7 or NFPA 318. An enhanced report, produced once for the equipment manufacturer, can save time and money for the end user by anticipating the questions asked when dealing with representatives of AHJs in different cities or countries.
The most significant benefit to end users from the S14 process is usually unseen, often involving design improvements that result from discussions during the evaluation. We have seen process liquid heating systems redesigned to include independent or redundant safety features, such as liquid level or over-temperature interlocks, or for the unnecessary use of combustible plastics to be reduced or even eliminated.
Although many reports end up highlighting electrical failures or overheating as the origin of the residual fire risk scenarios, this can mask the detailed work on which the report is based. During many fire risk assessments, our clients often seek advice on selection of “firesafe” plastics, defined by tests such as FM 4910—in particular, the complex problem of matching fire safety of materials to process compatibility.
As with fire safety programming in general, the key to successful implementation of an equipment fire risk assessment program is to work with the specialist consultant—preferably a professional fire engineer with relevant experience—from the early stages of product design, rather than considering S14 as a compliance activity to be applied in the month before shipment.
Al Brown is a professional fire engineer and director of Babtie Rushbrook (Glasgow, Scotland), specializing in fire risk consultancy for the semiconductor and cleanroom manufacturing industries. He can be reached at: [email protected]