Ballroom Cleanroom vs. Minienvironment
by Maria A. Lester, Associate Editor -- Semiconductor International, 4/1/2003
As technology used in the semiconductor industry advances, controlling contamination within a ballroom cleanroom environment becomes an increasingly difficult task. Until recently, there were not many options when choosing a cleanroom design. Within the last couple of years, minienvironments — in which a protective closure houses one process or tool instead of the entire production line — have become more predominant.
Minienvironments have even caught the attention of the Institute of Environmental Sciences and Technology (IEST, Rolling Meadows, Ill.), which publishes a series of recommended practice protocols for contamination control in cleanrooms. In response to this emerging trend, IEST released a new Contamination Control Recommended Practice on Minienvironments, IEST-RP-CC028.1. The document provides a framework for describing minienvironments for microelectronics. It discusses applications, planning, design and evaluation in detail.
In retrospect, the obvious advantages of using a minienvironment over a ballroom cleanroom environment appear to include:
- Controlling contamination within a single process is more efficient and provides better quality control than in a ballroom.
- The production environment is isolated from pollutants, and especially from operators. Wafers enter and exit through automated pass-through between the interior of the minienvironment and the environmentally isolated pods that deliver and retrieve cassettes of wafers and transport them between other process stations. Perhaps the other process stations are also housed within minienvironments.
- Enclosing all wafer processing and transporting tools within minienvironments reduces the requirements on air quality in the space surrounding the tools.
Perhaps the semiconductor manufacturing workforce will not need bunny suits and wafer-protecting gear in the future. Most likely there will be a place and purpose for each environment.
For additional information on clean processing, go to www.semiconductor.net/clean
