Nanonex NX-2500

1. Substrate Clean – solvent clean, acetone, IPA
2. PECVD oxide – GSI 200nm
3. AS200/620-7i lithography module/ASML-DUV

a). HMDS vapor prime
b). BARC apply, bake
c). 620-7i/deep UV resist apply
d). soft bake, hotplate
e). exposure
f). develop – Hamatech

4. BARC etch – Oxford 82
5. Oxide RIE – Oxford 80, CHF3/O2
6. Photoresist removal – Oxford 80
7. Silicon RIE – PT770 or PT720 Cl2 chemistry timed etch
8. Profilometry/interferometry
9. Oxide removal – Buffered oxide etch
10. Anti-stiction application – FOTS – MVD tool

1. Substrate clean – Hot Piranha Hamatech Wafer Clean (Prog 1)
2. Sputter deposit 20nm chrome – CVC sputter system, use rotating chucks for improved uniformity
3. Lithography

a. either ASML (for features down to 300nm)

i. HMDS vapor prime – YES oven
ii. apply BARC – AR3-0.6, 4500rpm, 45sec, bake at 205ºC 90sec
iii. apply resist – UV210-0.6, 4500rpm, 45sec, bake at 135ºC 60sec
iv. expose – 25mJcm-2, bake at 115ºC 60sec
v. develop – Hamatech Prog 1 (MIF726, 60sec)
vi. ARC etch – Oxford 80, “AR3 ARC etch” recipe, 70sec

b. or AS-200 (for features down to 800nm)

4. Cr etch – Trion

a. Clean - 10min O2 with sapphire wafer in
b. Clean - 10min N2/Cl2 with sapphire wafer in
c. Season - 10min using “Standard Cr etch” recipe with CR target in
d. Etch template - 3min Cr etch using “Standard Cr etch” recipe (check mask has cleared)
e. Immediately after etch: DI H2O rinse, N2 dry (to prevent damage by Cl from etch)

5. Inspection – optical microscopy or SEM
6. Photoresist removal – Oxford 80, 2min O2 clean
7. Quartz etch – Oxford 82,

a. Clean – 10min O2
b. Clean – 10min N2/Cl2
c. Season – CHF4, 10min
d. Template etch – CF4, 3min (→ about 80nm depth)

8. Profilometry measurement
9. Inspection – optical microscopy or SEM
10. Cr strip – wet etch (use 10min Cr stripper in chem hood, Hamatech does not work)
11. FOTS (anti-stiction) application – MVD 100, 2min preclean, 10min reaction time, 10 purge cycles.

1. Oxford 81, 3min O2 clean with 5sccm CF4, both sides
2. Hamatech Hot Piranha – Prog 1 (Wafer clean) or Prog 2 (Mask clean – more thorough)
3. Reapply FOTS as necessary – check with contact angle measurement

Note that after coating a template with FOTS, the template should be good for ~100 imprints. You can safely use acetone, DI water, and the N2 gun on an FOTS-coated template for clearing away larger particles. The first imprint of a given run will almost always be a throwaway, as it cleans out any smaller particles still on the template. For this reason, it's a good idea to use a thicker resist layer for the first imprint.

- Imprint substrate clean – Hamatech
- Apply NXR-1025 thermoplastic resist – 1500rpm, 60sec, 250nm (thickness should exceed maximum protrusion height of the template)
- Bake at 150C for 1 min. on hotplate
- Imprint – NX-2500, 200psi, 120C
- Mold removal
- Pattern transfer – RIE of residual layer- Oxford 80, O2 chemistry
- Substrate etch – TBD
- SEM/AFM inspection/measurement of CDs, bias, etc.

Note that the first imprint of any run will almost always be a throwaway, as its resist cleans out any small particles from the template. For this reason, it's a good idea to use a thicker resist layer on the first imprint.

Preparation:

1. Log into the Nanonex on Coral.
2. Log into the computer: User: engineer PW: nx2500
3. 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.” It will take 2-5 minutes for the UV lamp to turn on; there’s an indicator that turns green in the LabVIEW program when it’s ready for imprint. Note that the lamp is sometimes used for other tools, so if you wait more than five minutes and the lamp doesn’t turn on, it’s probably not in the tool. Contact staff to have it replaced.
4. Turn on the UV lamp and wait for it to come on.
5. Set the adjustable hotplate in e-beam spinner room to 190ºC.
6. Imprint substrate clean – Hamatech Hot Piranha Prog 1.

Recipe for thicker resist for template cleaning (1st imprint):

1. Line the spinner in the e-beam room with beta wipes; these resists are not allowed down the drain!
2. Spincoat NXR-3022 underlayer resist – 3000 rpm, 3000 rpm/sec ramp, 60sec (→ 200nm). The resist should be in the box fridge next to the Nanonex.
3. Bake at 190ºC for 90sec. (optional - this is a throwaway imprint)
4. Spincoat NXR-2030 UV curable resist – 1000 rpm, 3000 rpm/sec ramp, 60sec (→ 125nm). You will want to turn off the room lights and the hood lights before spinning! Ambient light from the windows etc. should not be a problem. No post-bake.

Recipe for standard imprints:

1. Line the spinner in the e-beam room with beta wipes; these resists are not allowed down the drain!
2. Spincoat NXR-3022 underlayer resist – 3000 rpm, 3000 rpm/sec ramp, 60sec (→ 200nm). The resist should be in the box fridge next to the Nanonex.
3. Bake at 190ºC for 90sec. (optional - this is a throwaway imprint)
4. Spincoat NXR-2030 UV curable resist – 2000 rpm, 3000 rpm/sec ramp, 60sec (→ 90nm). You will want to turn off the room lights and the hood lights before spinning! Ambient light from the windows etc. should not be a problem. No post-bake.

Imprint:

1. Stretch large silicone disk across metal ring, fix with magnets – make as flat as possible.
2. 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.
3. Set imprint parameters: 50psi all steps, 3min processing time, 10sec UV on time, 25ºC pre- & process temp, 27ºC vent temp, 10sec UV exposure. Hit the square UV button (it should be green) to get it to save the exposure time. The temperature for the last unload step is higher, in case the room temp is slightly higher and the system refuses to vent.
4. Hit start. You will hear a number of loud thumps and hissing noises; this is normal. Note: Pump time should be 2 mins or more, pressure should drop to -14psi at this time. It is normal to see bubbles in the silicone disks upon process completion.
5. Template removal: the template and substrate can be firmly stuck together; 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. This is easiest if the quartz template is on table with molded wafer on top; slide the razor between the two and pry the wafer up. A squirt from an N2 gun can be helpful after partial separation. Once you have removed the template, you can get a quick check of your imprint by running either DI water or methanol over the surface. (Do not use acetone; it will strip the underlayer resist!)

Pattern transfer into substrate:

1. NXR-2030 descum etch – Oxford 82, 30 sccm CF4, 15 mTorr, 50 W, 1 min; if the plasma doesn't light, set the low-pressure strike parameters to 60 mTorr strike pressure, 10 V DC bias, ramp 10 (rate: 34nm/min)
2. NXR-3022 underlayer etch – Oxford 82, 50 sccm O2, 15 mTorr, 50 W, 3 min; if the plasma doesn't light, set the low-pressure strike parameters to 60 mTorr strike pressure, 10 V DC bias, ramp 10 (rate: 86nm/min) This etch transfers the pattern from the UV-curable resist into the underlayer resist.
3. Substrate etch – Unaxis, Photonics Etch, (NICKZOR1) (rate: 166nm/min, selectivity: ~4:1) This etch transfers the pattern from the underlayer resist into the substrate.
4. Inspection – optical, AFM or SEM