UPDATES:
- Chengyu Liu (CNF Fellow), 12/21/17
Imprint substrate clean – Hamatech Hot Piranha Program 1 Wafer Clean
Dehydrate – bake at 170C hotplate for at least 10 min
Optional: apply O2 plasma treatment for substrate preparation
Apply Omnicoat as adhesion promoter - dynamic spin at 500rpm, 100r/s, 5s and spin at 3000rpm, 300r/s, 30s
Bake at 200C for 1min (adjust the hotplate temperature in advance)
Line the spinner in the e-beam room with beta wipes; these resists are not allowed down the drain!
NOTE: mr-XNIL26 is light-sensitive and should not be exposed to direct daylight so be careful of handling the mr-XNIL26 resist bottle. It has to be handled under yellow light.
Apply mr-XNIL26-300nm UV imprint resist – 5000rpm, 1000rpm/s, 30s ->240nm thick (choose the spin speed based on your template feature height; resist height should be slightly higher than template feature height)
Soft-bake at 80C for 1min (adjust the hotplate temperature in advance)
Log into the Nanonex on Coral.
Log into the computer: User: engineer PW: nx2500
Log into the nanonex software (Nanonex Nanoimprint Machine Control V3.7, on the desktop) using the same username and password. When it asks if you want to do UV imprints, select “Yes.”
Stretch large silicone disk across metal ring, fix with magnets – make as flat as possible.
Clean the template by rinsing acetone, IPA, DI water and N2 blow dry it.
Load: small disk (on the bottom), substrate, template (on top), large disk on ring. Make sure the springs in the Nanonex drawer are completely under the large silicone disk ring.
Choose imprint recipe “mrXNIL26_10psi_30sUV”.
Hit start.
Template removal: use razor blade with caution as quartz chips easily. Be careful, and try to use a razor blade as little as possible — the resist you scrape up will end up on the edges of your template. Slide the blade in between the template and the wafer and carefully pry them apart.
SEM the resist profile and decide the etching time for descum etch
mr-XNIL26 descum etch – Oxford 80s, 50 sccm O2, 15 mTorr, 50 W, 1min30sec; if the plasma doesn't light, set the low-pressure strike parameters to 60 mTorr strike pressure, 10 V DC bias, ramp 10 (rate: ~125nm/min) (note: make sure that mr-XNIL26 residual resist is completely etched away)
Substrate etch - This etch transfers the pattern from the imprint resist into the substrate.
For Si substrate, Unaxis or Cobra
Photonics Etch, (NICKZOR1) rate: ~135nm/min, selectivity: ~3:1.
Bosch deep Si etch (0Trench), rate: ~0.54um/loop, selectivity: ~35:1.
HBr etch, rate: ~220nm/min, selectivity: ~4:1
For Si3N4 substrate, Oxford 100
CH2F2/high He nitride etch, rate: ~240nm/min, selectivity: ~2.2:1
Inspection – optical microscope, AFM or SEM
Remove residual resist – oxygen plasma stripping