Saturday, August 8, 2009

Is This a Convenient Time to Clean?

Asking if it’s a convenient time to clean is equivalent to asking: “Is this a convenient time to extract your impacted molars”? The simple answer is “No.” There’s never a convenient time to clean (or remove impacted molars). Cleaning does not have any associated technical glamour or appeal — it tends to be considered a necessary evil and is therefore always inconvenient.

No one comes to work in the morning excited about the prospect of cleaning. To make matters worse, often cleanroom surfaces don’t look any different after cleaning. Cleaning is also viewed as a disruption to the orderly flow of manufacturing; ostensibly, if you are cleaning, you cannot be making product.

On the one hand, cleaning is a recognized requirement for minimizing contamination in cleanrooms. But in practice, these activities are often postponed, compromised, or ignored. When this occurs, air-borne or contact-transferred contaminants will accumulate on critical surfaces and unless they are removed by regular cleaning activities — for example by wiping — these contaminants can affect processes, products and yield. It may seem incongruous that a low-technology activity such as the wiping of surfaces can be effective in controlling contamination in modern, totally-automated, multi-billion dollar semiconductor manufacturing facilities, but there is no substitute for the surface energy that wiping provides to remove contaminants and the subsequent containment of those contaminants within the wiper fabric.

A convenient time to clean occurs when operators are trained and when cleaning products (i.e., wipers) are conveniently available. Convenience, surprisingly, translates to protocol adherence, and consequently, cleaner cleanrooms. Regrettably, there’s still no convenient time to extract impacted

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