New!! WBSilicide features!

Mary Tang mtang at
Tue Jul 8 12:48:40 PDT 2008

Dear wbsilicide users --

This wet bench now requires that users enable the system to be able to 
use many bench functions.  The reason for this change is economic:  our 
single biggest materiel expense is nitrogen.  Our LN2 tank gets filled 
up about 3X/week.  We also seem to go through about 2-3X what other 
university labs of comparable size use.  So one ongoing program in our 
lab is N2 monitoring and reduction.  As you may have noticed, flow 
meters are being installed in various tools, including the wet benches.  
Lots of N2 is used to run the wet benches -- the spin-rinse dryers N2 
hogs, but N2 is also used to drive the pneumatic valves which actuate 
most of the wet bench functions, like draining.  (No, there is no 
convenient "clean dry air" hook up at the wet benches.)

Estimates put N2 use at all the wet benches up to perhaps 7%-10% of the 
total N2 use -- in the building.  Wet benches continuously consume 
nitrogen whether or not they are being used -- and the opportunity cost 
is significant, particularly when you consider the low utilization on 
most et benches (wbnitride, wbmetal.)

So, the plan is to place have N2 turn on at individual wet benches only 
when the bench is enabled; i.e., when someone actually needs to use it.  
There are some logistics that need to be worked out, so Jim H. is "bench 
testing" his set up at wbsilicide.  Once he's confident everything will 
work, the plan is to install this modification on all the wet benches.  
We are trusting this modification should be reasonably transparent to 
normal, appropriate bench use.

Any comments or questions about this modification are appreciated.

Your SNF Staff

Mary X. Tang, Ph.D.
Stanford Nanofabrication Facility
CIS Room 136, Mail Code 4070
Stanford, CA  94305
mtang at

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