Suyong,
       I am the founder of YES a company that has specialized in HMDS deposition
for the last 25 years.  First SiO2 is hydrophilic if you measure the contact
angle fresh out of the diffusion furnace it is 22 degrees.  Then do a vacuum
vapor prime with the prime time at 1 minute, the contact angle becomes 45
degrees, 2 minutes 53 degrees, 3 minutes 61 degrees, 4 minutes 68 degrees, 5
minutes 75 degrees.  Very hydrophobic.  It is now an excellent surface tension
for resist adhesion.  The best surface is one that matches the liquid surface
tension of the resist and for most positive resists this is a good figure.  If
you continue you can become what I call resistaphobic, the resist falls off the
wafer.  A number of my Biotech customers who generally use other silanes use
thickness measurement.  With either XPS or interferometers they look for 4,6, 10
15,20 Angstroms of thickness.  To me knowledge non of my customers are doing
thickness measurements on HMDS.  et me know if I can be of any further help.
Bill Moffat C.E.O. YES

-----Original Message-----
From: Suyong Jung [mailto:[email protected]]
Sent: Wednesday, June 02, 2004 11:19 AM
To: [email protected]
Subject: [mems-talk] HMDS onto SiO2


Hello folks

Is there somebody who knows the way to check the quality of HMDS coated on
SiO2.
 From the knowledge that I've collected so far, normally people try a
contact angle method, but
, as you know, SiO2 is also hydrophobic just like HMDS is.
I would like to check the qualify of HMDS, and the completeness of HMDS
monolayer coating onto the wafer as well.

Thanks in advance

Suyong




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