In addition to the optical (UV) sensitivity of SU-8, it also has the ability to
be fully crosslinked purely by thermal means - if you heat the SU-8 up to a high
enough temperature (~180 - 200:C), the PAG will still activate and cause the
SU-8 to crosslink.

Oftentimes, the substrate will heat up to 200:C or more in a sputter or
evaporation chamber, which will trigger the crosslink.

The suggestion made by one person to place the wafer on a cooling chuck to keep
it at a constant temperature is a good one (although maybe not for the same
reason that was thought).

Best Regards,
Chad Brubaker

EV Group
invent * innovate * implement
Senior Process Technology Engineer - Direct: +1 (480) 305 2414, Main: +1 (480)
305 2400 Fax: +1 (480) 305 2401
Cell: +1 (602) 321 6071
E-Mail: [email protected], Web: www.EVGroup.com


-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of [email protected]
Sent: Thursday, March 19, 2009 8:52 AM
To: [email protected]
Subject: Re: [mems-talk] Uncured SU-8 crack

Dear Dr.  Mihaela Carp,

thanks in advance for you suggestions. If i well understand you suggest me
to make the hard bake also to the Uncrosslinked part of the SU-8 , but i'm
afraid that doing the hard bake to the Uncrosslinked SU-8,  this last one
can undergoes to deformations losing its planar characteristics(Tg of
Uncrosslinked SU-8 is 550C)...with this omincoat there is the possibility
that the wrinkles in the uncrosslinked SU-8 doesn't appear?...However i'm
going to do the Hard bake in a vacuum oven i will inform you as soon as
possible of the results!

Thanks again!