Dear all,

I have a problem when dry etching polyimide with a resist (S1813) mask:
After stripping the resist with MEK it seems that some crosslinked
resist covers part of the PI. This problem is especially visible around
pads (gold) which are etched free (seems like the crosslinked resist is
clinging to the PI or resist sidewall).
We run this etch on an RIE tool with 300W, 100 sccm O2 and a pressure of
150 mTorr.

I had some success in avoiding this kind of residue by mixing the O2
with 20% CF4, reducing the power and increasing the pressure to about
250 mTorr, but this dramatically affects uniformity, with very slow etch
rate in the center and high etchrate on the edge of the tool.

I would be glad if anyone has some hints how to avoid this problem.

Thanks,

Ernst