by Robert P. Donovan
The answer you get to controversial questions strongly depends on whom you ask. That statement rings especially true when you're assessing the health effects of workers in semiconductor cleanrooms.
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The controversy arises not from the cleanroom concept itself, but from the production processes conducted within this specific type of cleanroom. A cleanroom can be a healthy environment, even aseptic. Consider, for example, young David who, for nearly 12 years, lived in a series of cleanroom-like enclosures, including a mobile cleanroom-like suit similar to that used by NASA to isolate astronauts returning from the moon.1
The original purpose of the NASA suit was to prevent the spreading of any inimical, extraterrestrial species inadvertently brought back by the astronauts before such species could be identified and controlled.
For David, the mobility and the cleanroom-like environment represented a major leap in the quality of his very limited lifestyle. David was born with an immune deficiency that made him vulnerable to many of the everyday bacteria and viruses that most people tolerate with no ill effects. He needed to be completely isolated from contact with any of these organisms, and the isolation chambers, as well as the NASA enclosure, did the job.
However, what goes on inside a semiconductor is a lot of wafer processing, using some highly toxic and hazardous materials. LaDou and Rohm in their article, “The international electronics industry,”2 label semiconductor manufacturing as “one of the most chemical-intensive industries ever conceived.” If this description makes the industry sound like the creation of some diabolically evil, secretive villains, perhaps it was so intended, for there are those who see management cover-up, denial and irresponsibility in every medical incident reported—or, as is sometimes alleged, not reported—by semiconductor cleanroom workers.
While no one denies the presence of toxic and potentially hazardous chemicals in manufacturing, the controversial issue is the adequacy of present understanding, safeguards and procedures. One group argues, passionately and with deep conviction, that medical histories and documented studies prove the inadequacy of present control measures.
However, records published by the Bureau of Labor Statistics classify semiconductors and related devices (Standard Industrial Code 3674) among the top 5 percent of the safest industries they monitor.3 Other reviewers conclude, “With the exception of some gallium arsenide wafer production operations, exposures during routine semiconductor production operations are well below allowable limits.”4 However, this conclusion does not directly address the adequacy of the current “allowable limits.”
The semiconductor worker health issue is far from settled. What is clear is the high interest and concern for the health and safety of workers that continues on the part of government regulators, occupational healthcare professionals and semiconductor manufacturers.
The problems are not fully understood and agreed upon, but, at the same time, they're not being ignored or swept under the table. These efforts will undoubtedly remain a significant environmental standards and health activity for the foreseeable future, especially given the changing technology and practices of this still highly evolving industry.
Robert Donovan is a process engineer assigned to the Sandia National Laboratories as a contract employee by L&M Technologies Inc., Albuquerque, NM. His Sandia project work is developing technology for recycling spent rinse waters from semiconductor wet benches.
References
- “National Museum of American History Accepts Medical and Personal Artifacts of David, the Boy Who Lived in Bubble-like Environment,” Smithsonian News Release, March 20, 1986.