Hi all,
          I have a query about thermal evaporated Cu. I am trying to do a lift
off of metal electrode with Cr ( 300 A) as an adhesion layer
with 0.5 - 1.0 um Cu as top electrode. The Cr layer is deposited by sputtering
and the Cu layer by thermal evaporation. The stack is
( Alumina substrate / ferroelectric thin film / LOR 5A / Shipley 1813 / Cr /
Cu.)

However during  lift off the Cu layer peels off and only the Cr layer
remains.However the pattern looks good. Earlier I had done  Cr
layer deposition and Cu layer deposition by sputtering and never had a problem
with Cu peeling off during lift off. I am puzzled as to
why the Cu peels off now that I am doing thermal evaporation.

here are the parameters that i use during thermal evaporation:-

Current - 250 A
Voltage - 1.8 V
Target to substrate distance = 5 inches.
Base pressure - 4.0 exp(-6) torr
Chamber pressure - 8.0 exp (-5) torr .
time = 30 min for 0.5 um Cu


I would greatly appreciate if some one could give me some info on this and share
their experience with lift of thermally evaporated
Copper.

               Thanks in advance,
                          Dipankar Ghosh
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