------- Forwarded Message

Date:    Tue, 23 Sep 1997 00:41:13 -0500
From:    Phil Lamarre 
To:      info-mems
Subject: enhance sticking of PMMA

Hi Andreas,

There is a very simple way to make PMMA adhere better. Dilute a common
azide based resist (Almost any AZ or Shipley resist will do.) until you
get a very thin film ~ 20 Angstroms thick. First spin the very thin
azide resist on the wafer and then spin the PMMA as you normally would.
When you bake the PMMA at 180 degrees C, the azide based resist will
cross-link to the surface, making the PMMA adhere very well. The azide
based resist is very thin so a short oxygen plasma cleans up any residue
after patterning. This method is discussed in the publication (Lamarre,
P. and McTaggart, R., "A Positive Photoresist Adhesion Promoter for PMMA
on GaAs MESFETs", IEEE Transactions on Electron Devices, Vol. 37, No.
11, November 1990.) Good luck. If you have any questions about this
method, please feel free to contact me by e-mail or phone.

warm regards,
Phil Lamarre, USA
phone (781) 899-6733
e-mail Lamarre@earthlink.net

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From: Andreas Pecher 
To: mems
Date: Tue, 03 Jun 1997 18:12:05 +0200
Message-Id: <33944255.6DD5@wpfx31.physik.uni-wuerzburg.de>
Subject: enhance sticking of PMMA

We are using PMMA as a resist for electron beam lithography on GaAs
substrate. A typical size for our structures is several 10nm up several
100nm. PMMA
is used with a thickness of about 60nm.

Resently we wanted to create more complex structures. Unfortunately the
sticking of PMMA is not high enough and therefore the structures became
unstable
during the development step (due to surface tension and other effects).

Does anyone know of a material that increases the sticking of PMMA to
GaAs?

Thank you for your help!

Best regards,

Andreas Pecher

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Andreas Pecher
Technische Physik
Universitaet Wuerzburg
Am Hubland
97074 Wuerzburg
Germany
Tel: ++49-931-888-5173
FAX: ++49-931-888-5143
e-mail: pecher@physik.uni-wuerzburg.de

Privat:
Schulstr. 13
97297 Waldbuettelbrunn
Germany
Tel: ++49-931-49971

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