SU-8 developer is actually a pure solvent: Propylene Glycol Monomethyl Ether
Acetate (or, PGMEA). It is a common solvent found in many positive
photoresists, such as AZP4620.
By my understanding, the purpose of using IPA as a rinse solvent is simply
because it has the following two properties:
1) It is commonly available
2) It has a higher vapor pressure than PGMEA, and thus dries more easily.
It performs the rinse simply as a replacement solvent; that is, as you add IPA,
the material that flows off of the wafer is a combination of IPA and PGMEA.
Over time, since IPA is continuously added, the concentration of PGMEA reduces.
Additionally, in a two solvent system, the material that evaporates off will
contain both solvents (although richer in the higher vapor pressure solvent - in
this case, IPA), with the combined vapor pressure being higher than the vapor
pressure of the least volatile solvent (PGMEA). This will cause any residual
PGMEA to dry off much faster.
However, as is mentioned in the website referenced, if development is not
complete, then sometimes a reaction can take place when the IPA is added,
resulting in a white filmy residue on the wafer.
I have actually taken to using AZ EBR 70/30 as my rinse solvent for developing
SU-8 wafers. It is actually a combination of PGME (70%) and PGMEA (30%), with a
resulting vapor pressure very close to that of IPA. However, since the solvents
are completely compatible with the SU-8 developer, and with unexposed SU-8,
there is no possibility of reaction.
Best Regards,
Chad Brubaker
EV Group invent ? innovate ? implement
Technology - Tel: (602) 437-9492, Fax: (602)437-9435 e-mail:
[email protected], www.EVGroup.com
This message and any attachments contain confidential or privileged information,
which is intended for the named addressee(s) only. If you have received it in
error, please notify the sender immediately and then delete this e-mail. Please
note that unauthorized review, copying, disclosing, distributing or otherwise
making use of the information is strictly prohibited.
-----Original Message-----
From: [email protected] [mailto:mems-talk-
[email protected]]On Behalf Of suitto kk
Sent: Sunday, May 02, 2004 9:05 PM
To: [email protected]
Subject: [mems-talk] Rinsing using IPA
IPA is listed as a standard rinsing agent by Microchem.
However, the discussion in
http://aveclafaux.freeservers.com/SU-8.html
suggested IPA may not be most appropriate.
I would like to query what is the exact functionality of
IPA as rinsing? What actually happens when we rinsed the
substrate developed in SU-8 standard developer? Does the
IPA molecules "takes out" the SU-8 developer molecule by
chemically adhering to it and then evaporates quickly with
it, or it works on other mechanism? We mixed IPA and SU-8
standard developer and found that the two does not mix.
What does SU-8 developer actually contains?
Comments and suggestions are welcomed. Thanks for reading
this.
__________________________________________________
Do You Yahoo!?
http://bb.yahoo.co.jp/
_______________________________________________
[email protected] mailing list: to unsubscribe or change your list
options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk
Hosted by the MEMS Exchange, providers of MEMS processing services.
Visit us at http://www.memsnet.org/
