Hi All,
I am having some troubles with fabrication air-bridges on Si. The dimensions
of the air-bridges are: height 1.6um, length 90um, width 20um. I use double
layer AZ5214 and electroplated gold. My process is as follows: patten first
PR layer--> evaporate Ti/Au seed layer--> patten second PR layer-->
electroplating gold (~1.8um thick)--> AZ300T or NMP to strip PR.

The problem is that bubbles appear after the second PR layer baking(90deg,
2min). I have to do a long hard bake(120deg, 30min) for the first PR layer
to prevent these bubbles. But it would be very difficult to remove the first
hard baked PR layer in the last step. The air-bridges won't release. Is it
because the first PR layer has been baked too long? Or the AZ300T just could
not squeeze through the 1.6um slit to touch the PR? Thank you for the input!

Crayon Fu
University of Virginia