Care and handling of vacuum wands ...

John Shott shott at stanford.edu
Fri Jun 4 08:08:57 PDT 2010


SNF Lab Members:

You have likely noticed that we have made some changes to the vacuum 
wands in the cleanroom.  In particular, they are now being held in 
plastic supports that make it easier to keep the "business end" of the 
wand from hitting nearby sources of contamination such as walls, plastic 
tubing, etc.  We have also placed a quartz sheath around the stainless 
steel shaft in hopes of reducing the chances that accidental contact 
between stainless steel and clean wafers, boat, or cantilevers can cause 
metal-induced contamination.

Given the fact that a number of these vacuum wands have chipped quartz 
tips and we've already replaced quartz sheaths, it is clear that some 
are not handling these items with sufficient care.

In general, these quartz tips are the one thing that is allowed to touch 
a wafer after they have been cleaned and before they go into most 
high-temperature operations.  As a result, it is essential that everyone 
handle these with extreme care.  The quartz tip and sheath should never 
touch anything but your wafers, they should never be bumped against 
anything, nor should they ever be touched with a gloved hand.  Over and 
above their cost ... each tip costs $155 ... careful handling of these 
quartz vacuum wands is vital to those who have the most critical 
cleanliness needs.  Even if you believe that your wafers do not have 
critical cleanliness requirements, a number of people in the lab are 
processing wafers that are exceedingly sensitive to contamination.  If 
you contaminate the quartz tips in any way, their devices will likely 
suffer.

Please be particularly careful when handling the quartz-tipped vacuum wands.

Thank you for your continued support,

John




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