Plasma treat the surface with Argon followed by vacuum dehydration and
while under vacuum use vaporized OTS to react with the prepared surface.
Works with silicon, glass, stainless steel, ceramics etc.  With a PTFE
coating you will get a contact angle of 120 degrees, quite hydrophobic.
If you use heptadecafluorotrichlorosilane, you get contact angles of 130
degrees. Very hydrophobic, PTFE has 13 fluorine's hepta has 17.  There
are other silanes that have 21 and 25 fluorine's.  These are only
available in research quantities but contact angle close to 170 are
available using these.  Contact me for more information.

Bill Moffat, CEO
Yield Engineering Systems, Inc.
2185 Oakland Rd., San Jose, CA  95131
(408) 954-8353
cell 408 590 4577
bmoffat@yieldengineering.com
www.yieldengineering.com

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of Steven Yang
Sent: Thursday, March 01, 2007 9:08 PM
To: mems-talk@memsnet.org
Subject: [mems-talk] The pre-preparation for surface
hydrophobicmodification of silicon/glass

I proposed a pre-preparation process for silicon/glass wafer for their
later hydrophobic modification which use SAM materials, like OTS.
1. Hydration of wafer: Soak wafer in piranha solution at 100C for 20
mins 2. DI water rinse 10 mins 3. Methanol rinse 10 mins 4. RCA-1 clean
with H2O:NH4OH:H2O2 for 15mins 5. Dry with N2 gun

Is this process feasible for the later SAM modification based on your
experience? is it ok for both silicon and glass?

and I also try to compare the hydrophobic results which from SAM
modified sample to the one with PTFE spin coating. But for PTFE spin
coating on silicon/glass, what else need to take care if I take the same
process as above for the pre-preparation?