Sample preparation

SAMPLE PREPARATION

Wet etching recipe

1. Cleaning of the 2inch wafer (Organic clean).
2. 2 min drying on hot plate.
3. Spin coating of PMMA A2 495 --> 4000 rpm , resulting in ~ 70 nm of PMMA
4. 5 min annealing on hot plate.
5. E-beam writing.
6. Developing.
7. Wet etching HF (50%) : H2O = 1:50, 20 sec - 50 sec
8. Dissolving PMMA in acetone.
9. Cleaning in IPA, O2 plasma.
10. SEM and AFM observation.

Dry etching recipe

1. Cleaning of the 2inch GaAs wafer with deposited SiO2 (Organic clean).
2. 2 min drying on hot plate.
3. Spin coating of ZEP 4:1 (20%) --> 4000 rpm , resulting in ~ 40 nm of ZEP
4. 5 min annealing on hot plate.
5. E-beam writing.
6. Developing.
7. Dry etching in SPTS Z2 (CMi) Recipe "Si3N4 smooth" 12 second - etch rate 170 nm/min.
8. Final wet etch in HF 2% for 5 sec (dipping) to smooth the surface
9. Cleaning in Tepla Gigabatch (CMi Zone 2) - 10 min High power recipe
10. SEM and AFM observation.
Transfer to MOCVD.
To do near the MOCVD tool:
11. Additional organic clean (?)
12. Native oxide etch in HCl:H2O = 1:1 for several seconds

The preliminary results on the fabrication process

1. 26/07/2016 - Holes etching optimizing by wet etch recipe. PPT file

2. 12/8/2016 - Dry etch recipe optimizing