Dear All,
I am depositing a layer of Cr followed by a Pt layer onto patterned
AZ4533 using a Nordiko 8550. The work is a 6" Si wafer, HMDS prime
(vapour oven) and AZ4533 is put down, patterned and developed. The wafer
is sputter-etched in the Nordiko to remove the surface contamination of
the wafer, after which the Cr & Pt are deposited. After dep, the resist
is removed with acetone tank soak lift off, with a few minutes of
ultrasonic to hurry along the proceedings. Stubborn pieces of metal are
removed with acetone in a squeezy bottle. all of which does a pretty
good job. However, when lift off is complete there is a residue left
behind, which can be seen clearly when viewed at an oblique angle. I
read that this could be due to the dep process taking the work above the
softbake temperature of the resist, so I changed some dep
characteristics to ensure this doesn't happen, but the residue remains.
Does anyone have any tips on what the residue is (some artefact of the
resist, I'm assuming) and what I can do to prevent it?
In my application, post dep cleanup must be kept to a minimum, so
prevention is eminently preferable to a cure.
Many Thanks in Advance,
Darren.

Darren Slade

Semiconductor Process Engineer
SELEX Sensors & Airborne Systems
PO Box 217
Millbrook Industrial Estate
Southampton
United Kingdom
SO15 0EG
Tel: +44 (0) 2380 316834
Fax: +44 (0) 2380 316777
e-mail: [email protected]