PGMI/PMMA double layer resit recipe
Application
PGMI: PolydiethylGlutarimide, solved in cyclopentanone (75%) and Tetrahydroferylaclohol (25%)
tone | positive |
use | double layer resist for lift-off mask |
reference | Data sheets available from Microchem |
spin coat and pre bake | First layer: PGMI, 7%, 2600 rpm 5 minutes on hotplate @ 200 0C second layer: PMMA 950 K 2% in Anisol, 6000 rpm 2 minutes on hotplate @175oC (for thicknesses < 500nm) or 30 minutes on hotplate @ 175oC (for thicknesses > 500nm) |
exposure | about 1200 µC/cm2 @ 100 kV |
development | 60 s in MIBK : IPA = 1 : 3 30 s in IPA 10 s in MF 321 15 s in Water 10 s rinse in IPA |
limitations | Due to undercut, line separation must be more than 400nm. Lift-off has to be done with PRS, acetone can not be used |
Results: SEM micrographs
Optical microscope
After PMMA development, before PGMI development
After PGMI development
Deposition of Ti 10 nm, Au 80 nm (e-gun evaporation).
Liftoff in PRS or PRS, 80 degree C for 2hours (Lift-off not in acetone!!)
SEM inspection after lift-off
