If you do a solvent clean, your substrate will have a layer of organic
molecules clinging to the surface. It might be several molecules thick.
Your solvent might have some fractions of higher molecular weight
compounds also (high boilers is the slang term) or with different side
groups. The spec. for an electronic solvent concerns itself with metals.
Some solvents may have some water in them.

So with a dehydrate bake you bake off any organics off the surface,
water, alcohols, aromatics, alkanes, etc. Baking, raising the
temperature of a surface will favor desorption of anything held on by
Vander Waals forces, dipole forces, and even chemically bonded
materials.

Knowing what a specific solvent referred to here would be useful to
know.

Edward H. Sebesta
Independent MEMS and Semiconductor Engineer

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Evelyn B
Sent: Saturday, February 07, 2009 10:00 AM
To: General MEMS discussion; Evelyn Benabe
Subject: [mems-talk] Dehydration bake


I have seen dehydration bakes used as part of solvent cleaning of glass
and sapphire substrates. What is the purpose/advantage of this bake?