durusmail: mems-talk: Resist Coating Large Scale Conformal/Ogave surfaces
Resist Coating Large Scale Conformal/Ogave surfaces
2007-02-20
2007-02-20
2007-02-20
2007-02-20
2007-02-21
Resist Coating Large Scale Conformal/Ogave surfaces
Bill Moffat
2007-02-20
David,
      I think we have talked about a different problem.  The goobers are
a function of your coater and how you operate it.  If you are using wet
HMDS sprayed on before resist coating the most common problem is a drip
from the HMDS nozzle at the wrong time.  If this is the problem the
boogers are radial with a nearly round head say 10 microns in diameter
and a comet tail out to the edge of the wafer.  They can also be a
function of your coater exhaust.  If you ramp up fast and use a high
speed camera you will see a mist of resist over the wafer as you ramp
up.  If your exhaust is poor some of these resist balls will settle back
on the wafer. I did an interesting experiment with an old 4 track system
plotting round defects.  With the exhaust at the back, the back track
had no defects.  The next to the back had say dozens, the next track had
hundreds and the front track the farthest from the exhaust had
thousands.  Give me a call if you can and we can talk resist track
problems.
Bill Moffat, CEO
Yield Engineering Systems, Inc.
2185 Oakland Rd., San Jose, CA  95131
(408) 954-8353
cell 408 590 4577
bmoffat@yieldengineering.com

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