Dipankar,

I can only help with the second question because your first is too confusing.
Cr and Cu are the 2 worst metals to do
lift-off
with.  You have a sputtering/evap system?  Sputtering is very hot and will
damage your resist.  This is not recommended.
Second question:  If you do an O2 ash before your metal, you will take off the
edge (over hang) needed for good lift-off
from
your resist.  I would never ash a lift-off sample.

Brent

dipankar ghosh wrote:

> Hi all,
>        As a follow up to the above question , does ashing the sample with the
PR in an Oxygen plasma help in the lift off
> process ( by cleaning up the remnant undesireable PR that is left).
>     Please let me know,
>                 Thanks
>                       Dipankar
>
> ----- Original Message -----
> From: "dipankar ghosh" 
> Date: Mon, 11 Oct 2004 10:18:50 -0500
> To: "General MEMS discussion" 
> Subject: [mems-talk] Problems with thermal evaporation
>
> > Hi all ,
> >          I have some problems with thermal evaporation. I am trying to do a
lift off of Cu / Cr top electrodes using LOR
> 5A
> > and Shipley 1813 bi layer stack.I am doing in situ Cr sputtering and then Cu
evaporation without breaking vacuum.
> > I see that during the lift off process the metal patterns peel off. I get
good lift off of 0.25 um Cu/ 200 A Cr. However
> > when I do 0.5 um Cu/ 200 A Cr , I do not get good yield on the devices (
most of it peels off ).
> >