LITHOGRAPHY
S1813
1. Spin on – 40 sec @ 3,000 rpm. No spin-up step necessary
2. Hot plate bake – 60 sec @ 115 C (on an aluminum bake plate). Temperature setting is somewhat forgiving
3. Exposure – PHOTO1 for 10±2 sec. (depending on lamp brightness). Alignment gap ~ 100 um.
4. Development – 60 sec with agitation in MF-319
5. Rinse with DI H2O
6. Dry with N2
SU-8
1. Spin on – 10 sec @ 300 rpm then 30 sec @ 2,000 rpm. (500-1,000 rpm/sec acceleration)
2. Pre-exposure bake – 60 sec @ 93 C (on an aluminum bake plate). Temperature setting must be quite precise
3. Spin some S1813 onto a large junk Si wafer. Can use same recipe as above. This should form a thin film of wet S1813
4. Stick the sample onto the Si wafer from above. This should “glue” the sample to the wafer via the thin S1813 layer
5. Exposure – PHOTO 1 for 20-30 sec. (depending on lamp brightness). Use 2 small pieces of Si or Ge (whose thickness is identical to that of the sample) as “feet” to level the mask. Alignment gap = 70 um.
6. Remove from the backing (using tweezers to push the sample sideways and off of the resist “glue”
7. Clean the back of the sample with a Q-tip dipped in acetone to remove S1813 residue
8. Post-exposure bake – 120 sec @ 93 C (again, precise temperature)
9. Develop in SU-8 Developer for 3 min using a magnetic stir bar
10. Rinse with IPA (not H2O)
11. Dry with N2
12. Hard bake – 15 min @ 190 C in an oven (not hot plate)
ETCHING
Nb Etch (RIE1 at Duke)
Run the following recipe: 130 mT pressure, 100 W RIE, CF4 = 40 sccm, O2 = 4 sccm. 30-40 sec. depending on the thickness.
Fe Etch (RIE2 at Duke)
Run the following recipe: 15 mT pressure (15 set, 17 measured), 300 W ICP, 125 W RIE, BCl3 = 5±1 sccm, Cl2 = 45±1 sccm. Length of time depends on thickness.
The recipe is to be run manually, rather than automatically, because the BCl3 flow rate tends to fluctuate. Wait for it to stabilize, then turn on plasma by hand.