>>New manufacturing facilities for leading edge processes, i.e., approaching 100nm nowadays, are class 1, I believe. I would guess that 10,000/1000 is at the low end of the scale.<<
Your observations are very well on the mark re need for class 1 SELECTIVELY for present day sub-micron semiconductor wafer processing. Some tidbits I recall from my own experience and recent readings include:
Standard factory environment might have 10-20 million particles/ft^3 so the 10000/1000 is orders of magnitude better.
I would expect that the overall room is at a class 10000 with individual hoods giving localized class 1000 cleanliness.
To the extent that a cleaner environment is needed a separate mini-environment could be established and maintained, e.g. using so-called SMIF (Standard Mechanical Interface) boxes for storing and transporting wafers as well as being the in-out interface for the likes of a sputter, etching or other operation.
The clean room environment also includes other controls, e.g. temperature, humidity, electrostatic buildup.
Finally, the personnel within the clean room will dress accordingly to maintain the standards. Hair, flakes from makeup and dry skin, spittle, etc would all be reduced significantly even with a moderate dress code.
The relatively small areas required for developmental test structures are fully consistent with this (10000/1000) environment IMO
Ed |
