20210310
From mn.fysikk.laglivlab
- Started with new SU8
- Took it out from the fridge at 09:00
- Transferred to a new syringe
- Let out inside alu foil to thermalize
- new wafer cleaned for dust with IP, plasma treated and then 160 C for 7-8 min
- changed spin program to 970 rpm to achieve 890 rpm on the readout -> 100 um thick layer.
- transferred su8 from syringe
- forgot to leave it some minutes on the wafer to thermalize before spinning
- spun for 60s at 890 rpm (readout)
- leave for 10 minutes on spin coater
- to keep the hot plate at 95C beyonf 99.9 min I programmed a third period: 40 + 80 min
- back 4 hours later due to a belated meeting
- turned the mask the other way because I checked once more which was up and it was confirmed by what I saw in the microscope
- transferred wafer to UV-KUB, had the light on for some seconds (big mistake)
- chose 600 um thickness to press mask onto wafer (see later: maybe not enough?)
- used 44s at 50% to have 1000 mJ/cm^2
- post baked
- developing delayed 2-3 hours due to meeting (is this bad?)
- Same problem as before:
- small structures are not removed by developer
- differences on the wafer in how well small structures are developed
- developed 5 min according to table, but no small structures developed
- continued several rounds up to 11 min, from 8-9 min nothing seemed to change