On wo, 2021-04-28 at 11:23 +0200, Martin Geisse wrote:
Hi,

- spin coating

I finally tried to build a makeshift spin coater the way Sam Zeloof did, by mounting a plastic can on top of a CPU fan (actually a case fan from another device I had lying around). I can't say this is the way to go... the fan is way too weak to spin the can at a meaningful speed. It is also very hard to center the can exactly, so it wobbles a lot and that probably reduces the speed even more. Mounting a die without a container would allow the fan to spin faster, but would likely clog the fan with chemicals in no time. I'll next try my original idea, to mount the can to an axle that I'll stick into a power drill.

One thing I did find out is that the coating liquid should be evenly applied before spinning. It will NOT spread to the whole surface by itself, but rather run to a single direction in a concentrated stream, probably due to surface tension.

If I remember correctly the spin coaters used in clean rooms first spin up the wafer and then dispense the liquid. You need to dispense liquid in middle of wafer as liquid will online move outwards.

greets,
Staf.