Hi

I have a combination of PMMA and photoresist AZ3312 on an oxide substrate
that was hard baked
to 170 C for 2 minutes. The film appears shattered like a piece of glass and
the thickness is
anywhere from 0.01-0.1 um. The resist is really stubborn and has not yielded
to any of the
following methods so far -

- Microstrip 2001 at 70 C for 1 hour
- Asher at 200W for 4 hours
- Piranha clean at 100 C for 3 hours
- AZ 300MIF developer for 1 hour
- Acetone at ambient for 1 day
- Acetone at 50 C in Ultrasonic bath for 3 hours
- Nano-remover PG at 80 C for 3 hours
- Nano-remover PG at ambient for 4 days
- Nano-remover PG at 50 C in Ultrasonic bath for 1 hour

Has anyone ever had to deal with the removal of extremely hard baked
photoresist?
Any suggestions will be greatly appreciated!

Thanks,
-Ameya