It is possible but you should maybe use a bi layer of LOR and the Shipley
atop. As you know, the bake of LOR layers determinates the under-etch rate
of LOR after exposure and development of the Top photoresist. You should try
to back at 200°C during 4 or 6 min at least otherwise your cap layer will
breakdown during the metal deposition.

Be careful about your first layer of LOR. Do not bake it too hard because
you will create a stair shape of resist, making some trouble for the
lift-off especially if you are using sputtering.

About aspect ratios, the main problem is the areas between the features and
not their width. Such process is not suited for high densities electrodes
integration. You should keep at least 20µm between the features otherwise it
wont be possible to remove the remaining metal between them



Philippe Muller


----- Original Message -----
From: "dipankar ghosh" 
To: 
Sent: Tuesday, September 28, 2004 5:11 AM
Subject: [mems-talk] Metal Lift off using LOR 20 B and Shipley 1813


> Hi all,
>         I am trying to do a lift off of 2 um Cu / 200 A Cr layer with 5 um
features using a bi layer lift off process using Microchem LOR 20 B and
Shipley 1813. Does anybody have any experience using this .Could you pls
share your process details.
>      Also what are the limitations of aspect ratio on bi layer
photolithography process? Is it possible to do 3 um features of 2 um thick
metal using this process.
>          Thanks in advance,
>                  Dipankar Ghosh
> --
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