Dear colleague,
if you need to cross-link PMMA as a film you can find my information useful.
PMMA starts to crosslink under high dose of actinic irradiation. For
example, being well known as the high resolution positive electron
resist it behaves in this way till the electron dose does not exceed
approximately (1-5)*10^(-3)C/cm^2. This dose value, when crosslinking in
PMMA starts to appear, depends on the voltage, the substrate and the
film thickness. At doses about 10^(-1)C/cm^2 the PMMA film is
practically not solved in all PMMA developers.
The idea to use PMMA as a negative resist is not nice. It will have low
contrast  and it is not possible to dissolve it in solvents usually used
in microfabrication if it needs to be removed. But it can be easily
removed in O-plasma.  PMMA film, when crosslinked, can serve as an
insulating layer in some laboratory micro- or nano-devices. Which
irradiation to use (UV- or electron) depends on the film thickness. UV
does not penetrate deep. At crosslinking the film thickness shrinks
because low volatile products which are formed during irradiation leave
the polymer.
Sincerely, T.Borzenko.
___________________________________________________________________________
Dr.T.Borzenko
EP3
Physikalisches Institut der Universitaet Wuerzburg
Am Hubland 97074 Wuerzburg
Deutschland
tel +49 931 8885876
fax +49 931 8885142
e-mail:    borzenko@physik.uni-wuerzburg.de


___________________________________________________________________________

Original message:

>Message: 2
>From: "Emer O'Reilly" 
>To: 
>Date: Tue, 20 Aug 2002 17:38:48 +0100
>Subject: [mems-talk] crosslinking PMMA
>Reply-To: mems-talk@memsnet.org

>Dear all,

>Would anyone be able to direct me towards some information please: I wish >to
>find out how to cross link PMMA.

>Thanks in advance.

>Emer.


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