You might also try either reducing the power output of the exposure, ie
adjust the intensity not only the time; or, if your Karl Suss does not allow
for an intensity adjustment (the MA150 does however), you could get the same
effect by using a neutral density filter, if you had one for your system.
The reduced power/intensity of exposure to the wafer may also help slow down
the formation of the nitrogen.

-Justin
Justin C. Borski
MEMS Program Manager
Advanced MicroSensors Inc.
[email protected]
www.advancedmicrosensors.com



-----Original Message-----
From: Kirt & Erika Zipf-Williams [mailto:[email protected]]
Sent: Monday, April 28, 2003 2:08 PM
To: General MEMS discussion
Subject: Re: [mems-talk] mouse bites in photoresist


You are on the right track with reducing the exposure.
The mouse bites are probably from nitrogen that is evolved in novolac
resists during exposure.
One solution is do part of the exposure, wait a minute so the nitrogen can
diffusively spread,
then complete the exposure, in sort of a pulsed exposure mode.
I think Suss designed this ability into some of their older aligners.
If your system does not allow such a pulsed exposure, at least try waiting
10 minutes before developing
so the nitrogen can diffuse.
    --Kirt Williams, Ph.D.   consultant

----- Original Message -----
From: Magali Brunet 
To: 
Sent: Thursday, April 24, 2003 9:50 AM
Subject: [mems-talk] mouse bites in photoresist


> Hi All,
>
> I am spinning a thick photoresist (novolac-type): around 60um. The bake is
> done at 90C for 40min.
> After exposure (typically 1680mJ/cm2), we are seeing mouse bites on the
> photoresist near the exposed area.
>
> I've tried to reduce the exposure time but without success.
>
> As anyone experienced this as well? would anyone know how to get rid of
> these mouse bites?
>
> Thanks a lot in advance
>
> Magali Brunet
>
> --
> Energy Processing for ICT
> NMRC, Lee Maltings, Cork, Ireland
>
> Tel: +353 (0)21 4 904279
> Fax: +353 (0)21 4 270271
>
>
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