Musical wet benches (wbdiff down.)

Mary Tang mtang at
Sat Feb 23 22:13:41 PST 2008

Hi all --

Robin reports that the thermocouple in the sulfuric hot pot at wbdiff 
appears blackened so that it may possibly have become contaminated.  
(Please do not be alarmed if you used this station - there is a teflon 
sheath around the TC which should prevent significant leaching -- and 
subsequent HCl and HF dips should remove trace metals.)  So, wbdiff is 
shutdown until this TC can be replaced by Jim H or other maintenance 
staffer and pot decontaminated.

While wbdiff is shutdown, Robin is starting decontamination procedures 
on wbsilicide, so that it can be used for pre-diffusion cleans.  This 
will consist of pouring 5:1:1 H2O:HCl:H2O2 into the hot pots, HF tank, 
and dump rinsers.  She's generously agreed to start this -- whoever 
needs this might need to finish it -- please check Coral for updated 
status reports.

Unfortunately, it appears that the wbsilicide spin rinse dryer is not 
working (as per the last reported comment).  If that is indeed, the 
case, I'm afraid users will have to walk their wafers over to the wbdiff 
spin dryer.  (Inconvenient, I know, but just possibly better than the 
alternative of jumping back and forth between acid dips.)

Moreover, I've also been informed that we're out of 50:1 HF.  (Gee, no 
end of fun!)  Robin has kindly volunteered Eric to mix up a batch for 
tonight, if needed.  I'll come in the morning to stock up.

Again, apologies for the inconvenience -- Jim was out last week, but due 
back Monday.  I trust things will be straightened out then.  And if 
anyone has observations/suggestions/ideas about getting a handle on 
weekend acid shortages (we ensure stocks are full Fridays at 4 pm -- are 
there a lot of partial bottles?  why don't acid change logs seem to 
reflect shortages?  help!) they would be much appreciated.



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