ETMS2.com

By Chris Evanston, PE
Earth Tech Microelectronics Program Manager

When equipment manufacturers, first required evaluations to the SEMI S2 Guideline, in the early nineties, the process was often painful and costly. Equipment manufacturers would design and build their system and afterward the third party was called in to do a review. On the first day of the evaluation the third party would descend on the equipment manufacturer like a team of IRS auditors, with a group of mysterious sounding specialists. After three to five days of intense questions, testing, and poking around the tool, the third party would go as quickly as they came, leaving behind a preliminary findings report with anywhere from 25 to 250 non-compliance. The equipment manufacturer would have no alternative except to scramble together a redesign effort. In an attempt not to delay shipments, costly retrofits were often needed after installation. This pattern of design-evaluate-redesign may have been unavoidable when equipment manufacturers were just getting introduced to the SEMI S2 Guideline. However, it no longer makes any sense, and, the more seasoned equipment manufacturers have focused their efforts on compliance in the design phase of tool development.

General Approach to Designing Compliant Tools

The key to compliance in the design phase is to identify issues as early in the design process as possible and thus avoid redesign to the greatest extent possible. Fundamental to this is ensuring that the engineering project manager and design engineers understand in detail all the specific requirements their design must meet, so that they can design their tool to meet them. Therefore, getting very detailed information on specific design requirements to the design engineering team as early in the design process as possible is essential to accomplishing this objective. General information, which design engineers cannot directly use to produce compliant design, is not useful in obtaining this goal. Withholding specifics until prototypes have been built or designs have been completed is also not of value. Only by giving substantive information--before designs have been completed--can this approach add value by avoiding costly redesign. The following is a brief over view of how EARTH TECH Microelectronics has been supporting the design of compliant tools at some of the largest equipment manufacturers in the semiconductor industry.

Design Concept Review

The best time to start focusing on the designing a compliant tool is the concept phase of the project, before any design work has started. By providing EARTH TECH Microelectronics with an overview of the design concept before the design project has begun, many potential safety/compliance issues can be identified based on the experience of our team. EARTH TECH Microelectronics can follow up these discussions with a "Preliminary Issues List". This list of course contains no "non-compliance" because at this stage there is no design, which can be non-compliant. But it is a very effective way to inform the design team of potential pitfalls. This is in keeping with the general principle "the earlier the input the more cost effective it is". It is a pro-active way to identify potential problems before they become real problems that will drive costly redesign.

Project Plan Development and Integration

The next step in supporting a design project to ensure the outcome meets industry safety requirements is to understand the engineering project and integrate the safety compliance project plan with the overall project plan. To do this, an initial meeting with the engineering project manager will be required, in which he can give an overview of his project plan. Following this, it will be the responsibility of the EARTH TECH project manager to come back with a specific plan for fully integrating the EARTH TECH efforts with the engineering project plan. After this plan has been reviewed by the equipment manufacturer project manager, revised by the EARTH TECH project manager, and finally accepted by the project manager, a detailed plan will be established to support the equipment manufacturer engineering design project.

Training

A very cost effective way to help engineers avoid designing systems that violate industry safety standards is to train them on the basics of designing compliant tools. The challenge of developing such a course is to give engineers information they will find useful in their current projects without wasting their time with a lot of information that is only of valve to safety professionals. EARTH TECH Microelectronics has developed such a course with the needs of engineers and not third party evaluators in mind. One of the corner stones of the EARTH TECH Microelectronics approach to training is the modular concept. The modular as opposed to a general training approach is preferred because engineers do not want to waste time in training that is not going to do them any good with the design issues they are facing. In this way, interlock design engineers do not need to attend discussions of ventilation design, and mechanical engineers do not have to sit through discussions on electrical power distribution.

Ongoing Technical Support

Experience has shown that the immediate effect of training engineers is not less questions but more. This is a natural part of the education process. As engineers become aware of these issues, they will inevitably want more information and clarification as their design progress. This is another vital area where EARTH TECH Microelectronics can add value early in the process. Sometimes these consultations take place during a five-minute phone conversation. Other times they are facilitated by a few engineers discussing design options around a white board. Whatever form it takes, the key is that as design engineers become aware of the issues they will need a resource to answer questions. The EARTH TECH Microelectronics team members are particularly effective in meeting this need by providing a knowledgeable engineering resource to answer these questions.

Design Review

At the heart of any engineering design project are the subprojects where the engineering design takes place. The following are the key roles the EARTH TECH team would play in these subprojects. Often when design engineers are aware that a fully compliant design is part of their design specifications they will ask for informal reviews of portions of their designs to ensure there are no issues. These informal reviews of on going design work are an essential part of the process of designing a compliant tool. In addition to test informal reviews a formal review of all subsystem design ensures design efforts are consistent with the requirements of fully compliant design. This same process continues as the subprojects become fully integrated into a final design.

Alpha and Beta System Review

A comprehensive review on the alpha and beta system will be conducted. At this stage if the preceding steps have been followed this will be done with minimal effort. The most effective strategy for developing compliant tools is for the greatest intensity of effort to be early in the design project. The success of this effort permits the time spent on safety/compliance to taper off as the design matures. However, as it is needed the same type of support that was provided for the development of the project is provided during the Alpha and Beta stages of system development. Reviews of these systems ensures that remaining problems are resolved, while the same type of design support helps resolve them in the most effective way.

Final Product System Review and Testing

A comprehensive review and testing on the final production model will be conducted. This will be done in accordance with the EARTH TECH Microelectronics approach of tracing the flow all potentially hazardous energies through the system and reviewing all foreseeable human interfaces with the system. EARTH TECH Microelectronics team of electrical engineers, industrial hygienists, chemical engineers, ergonomists, and environmental engineers will cover all the key areas of a comprehensive SEMI S2 review. This will include the full body of industrial hygiene, ventilation, electrical, and environmental testing. The final ergonomics survey of will be conducted and the SESC checklist will be completed. This comprehensive review will include a review of the system manuals. Vital to a comprehensive final review will be the completion of the single fault analysis using established failure modes and effects, as well as HazOp techniques. A comprehensive final report will be issued following the evaluation to document its results. To avoid potential conflicts a different EARTH TECH Microelectronics team will be used to conduct the final review than was used to support the design effort. At this stage in the game few if any issues are found and those that are of a minor nature.

Cost Benefit and Positive Customer Perceptions

The cost benefit to this type of approach can be substantial. Even modest estimates put the savings at 50%, although in many cases it can be much higher. The biggest savings are in reduced engineering time because extensive redesign efforts are avoided. There are other benefits of course including improved customer perceptions. Instead of bringing a new tool to the market place and being compelled to explain to your potential customers why your product deviates from accepted industry safety standards, you can just say it complies and produce a detailed report to support that statement. Without question this helps create a strong positive image of both the workmanship that when into the tool design and the organization that produced it. This is why seasoned safety professionals have been wisely charting the course toward designing compliant tools.