20210309

This wafer was overdeveloped

Had left the insolated wafer on the hot plate over night. This means 15 hours rest instead of 10 min.
Table says 5 min develop.
I used new PGMEA
After 3 minutes I noticed white structures in the region around the main structures. I did not understand what this signified
After 5 min I rinsed with isopropanol (IP)
I struggled to get good view in the microscope. Therefore I miscalculated what I saw and thought I needed to develop more.
I developed about 30 s more.
In the microscope it was now clear that the structures where overdeveloped and all the smallest features where erased.

Time to start again

I lost all my edits! Obviously it's important to save before leaving idle

SU8 to wafer using syringe worked perfectly.
Used a single spin: ramp 100, 900 rpm at 40s
Display said it only spun at 830 RPM
Noticeable bulge at edge of wafer. Tried to wait for an hour, but it did not change much.
Transferred to hot plate: 65C 15min, 95C 90 min, should be 120, but display only has 2 digits. time manually.
We need a timer here! I am not really sure how much time it stayed at 95C, when I took it out the temp had dropped to 77C
Transferred to UV KUB, put mask on top and insolated for 22s
Transferred to hot plate after about 10 min when hot plate was at 60C.
Is there something wrong with how I put the mask on? The big structures are nice and square, but the small structures did not even make a indent in the surface.
=> check which side up of mask
=> try new SU8
=> take images with WLI

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