Hi Matthew,

I am not sure if your process allows this, but you can try a dummy metal
layer deposition and patterning just for alignment marks before the first
SU-8 layer. You can use image reversal and use the same mask as SU-8.

Best Regards
Serhan Ardanuc
SonicMEMS LAboratory
Cornell University


>From: mems-talk-request@memsnet.org
>Reply-To: mems-talk@memsnet.org
>To: mems-talk@memsnet.org
>Subject: MEMS-talk Digest, Vol 22, Issue 16
>Date: 16 Aug 2004 09:00:35 -0700



From: Matthew Davies 
Reply To: General MEMS discussion 
To: 
Subject: [mems-talk] Double depth SU-8
Sent: Monday, August 16, 2004 2:22 PM
Hi all

I’m trying to find out if there is an easy method for seeing developed
SU-8 through another layer of SU-8.  We are trying to make devices
requiring double depth processing and the aligning of the photomask for
the second layer is very difficult as we are currently unable to see the
developed SU-8 on the bottom layer.  At the moment we need to
overdevelop the bottom SU-8 layer until cracks appear at which point we
can see the cracks through the top layer of SU-8.

Any suggestions would be much appreciated.

Thanks all

Matt Davies
STRC, University of Hertfordshire

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