Ariel,
      The line edge roughness is due to trapped water molecules at the edges of
the developed lines.  If you use vacuum vapor prime you remove all the water on
the wafer.  This takes up to 15 minutes dependent upon the wafer surface.  Then
priming with HMDS while still under vacuum and still dehydrated the HMDS seals
the surface.  Moisture can not lift off the resist and more importantly for you
it can not break down the edges to produce edge roughness.  About 25 years ago I
was able to move a 0.8 micron dimension from +/- 10% variation to +/- 4% by
getting rid of edge roughness.  Bill Moffat

-----Original Message-----
From: Ariel Lipson (IC) [mailto:ariel.lipson@imperial.ac.uk]
Sent: Monday, February 09, 2004 8:36 AM
To: MEMS-talk@memsnet.org
Subject: [mems-talk] Line Edge Roughness


Hello,

    I'm trying to fabricate ~2um features in silicon using Shipley S1805
photoresist, but get rough resist edges (<0.5um). This problem is know as
"Line Edge Roughness". Does anyone have any suggestion how to reduce the effect.

Thanks, Ariel
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