Dear all,

I have some question regarding air-bridge fabrication. Thanks for
sharing and helping.

1. I plan to use AZ4210 as the 1st layer PR (2.9um thickness) to open
the VIA contact and reflow the PR to round the sidewall. Is 120C/30min
in oven appropriate for re-flow?

2. I will use e-beam evaporator to deposit seed metal layer (Ti/Au) for
carrying the electroplating current. What is the proper metal thickness
for this purpose? (500A vs. 1500A) What if I use sputter instead of
e-beam evaporate to deposit? My consideration is its efficiency of
electric conducting continuity and easiness to remove the 1st layer PR
later.

3. I will use AZ5218 as the 2nd layer PR (2.7um on planar surface). Will
the exposure, bake and develop condition remain the usual? My concern is
AZ5218 is now on top of another PR layer and locally it is much thicker
(greater than 5um) at Via contact.

4. After Au electroplating, what is the better way to remove the excess
seed metal layer? Do I have to use an extra etch step (dry or wet) to
remove it?

Wei Cheng