cleanliness/semi-cleanliness specifications

J Provine jprovine at
Tue Sep 14 21:51:29 PDT 2010

hi specmat,
what are the numbers associated with clean and semi-clean status in the snf.
 ie what density of  trace contaminants are allowed?  i tried to find this
information on the snf website but to no success.  i remember some of these
numbers being presented at a clean-tamination meeting last year.

for instance, two questions have arisen recently concerning the savannah:
1) clean wafer goes can we verify that it is clean or semi-clean
coming out?  what number do we need to hit with TXRF or other methods.

2) a user can purchase W with "low alkali content" from a company.  they
promise <20ppm of alkalis in the W filament (most of the contamination is
likely K).  is that semi-clean?

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