Hi So I've now set up the office here with tables and stuff and could reproduce your experiments. If we know which motor performs ok for building a cheap spin coater, I could actually build one a little bit more professionally, by ordering some of those motors from Aliexpress. We could then sell those coaters on eBay and finance LibreSilicon a bit with it.
What do you think?
Cheers -lev
On Wednesday, April 28, 2021 6:36:11 PM WEST Martin Geisse wrote:
Hi,
If I remember correctly the spin coaters used in clean rooms first spin
up the wafer and then dispense the liquid
That did the job. I still think that the RPM is quite low because the fan is too weak, and I might later switch to the power drill to improve that, but applying the liquid only after the motor is spinning is definitely very important.
You need to dispense liquid in middle of wafer as liquid will online move
outwards.
Obviously :)
I guess, you're experiencing problems because you didn't apply a primer
first.
I only did a test, spinning oil onto a coin. I guess that the primer helps with wetting and/or sticking to the wafer surface, which wasn't (yet) a problem in my test. Anyway, good to know!
Greetings, Martin
On Wed, Apr 28, 2021 at 5:06 PM David Lanzendörfer <
leviathan@libresilicon.com> wrote:
Exactly. First you've gotta spin up the wafer, and then you've gotta dispense it kind of towards the center, but it's not so critical. I guess, you're experiencing problems because you didn't apply a primer first.
https://www.3mdeutschland.de/3M/de_DE/unternehmen-de/produkte/~/3M-Silan-G las-Primer-Transparent-1-L-Flasche/?N=5002385+3294237313&rt=rud
Cheers -lev
On Wednesday, April 28, 2021 12:24:57 PM WEST Staf Verhaegen wrote:
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.
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