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<azonenberg>
o/ diginet
<azonenberg>
we were talking sol-gel TiN as a possible gate material not requiring vacuum
<diginet>
o/ azonenberg
<diginet>
yes
<diginet>
mind you that this is all theoretical
<diginet>
I haven't found much conclusively on doing sol-gel TiN
<azonenberg>
Most of the work here is
<azonenberg>
You could also potentially do it with relatively loose vacuum
<diginet>
TiN seems to be one of the most promising candidates for metal gates
<azonenberg>
like, reactive sputtering of a Ti target in Ar + N2 atmosphere
<diginet>
so that's encouraging
<azonenberg>
at tens to hundreds of mtorr
<diginet>
I think if it's possible with a harbor freight vacuum pump, then it's reasonable
<azonenberg>
Yeah
<diginet>
anything which requires more isn't
<azonenberg>
You can do sputtering with a relatively cheap 2-stage rotary vane pump
<azonenberg>
idk about harbor freight, but like united nuclear or something
<diginet>
sure sure
<azonenberg>
i have one that advertises 40 mtorr
<diginet>
the question is whether you can do it well
<azonenberg>
The sputter coater for SEM sample coating at RPI runs down to 30ish
<azonenberg>
you normally purge down to 30 then coat at 60
<diginet>
my goal is to eventually get the cost of the entire system to $5-6k. That's what the cost of early hobbyist 3D printers was. IMO anything more is unreasonable
<diginet>
*were
<diginet>
err
<diginet>
actually no was was right
<azonenberg>
Let's make something that works first
<diginet>
sure sure
<azonenberg>
also... grr
<azonenberg>
cant remember who the guy in canada that's trying to make a stepper is
<azonenberg>
he's been pming me and i forgot to tell him to take it to the channel
<diginet>
anyhow hard vacuum is generally not possible for an amateur, putting aside money the equipment is expensive and temperamental (at least the used stuff)
<azonenberg>
Yes, hard vacuum isnt
<diginet>
huh
<azonenberg>
But soft vacuum? Much more so
<diginet>
indeed
<azonenberg>
Especially relatively safe processes like sputtering
<azonenberg>
which dont leave the nasty wastes you get from RIE
<diginet>
is sputtering difficult to control?
<azonenberg>
Control what?
<azonenberg>
Film thickness? Deposition rate? Grain size?
<azonenberg>
Purity?
<azonenberg>
Density?
<diginet>
everything
<azonenberg>
AIUI the parameters available are pressure, gases, and current
<diginet>
mostly film thickness though
<azonenberg>
We could probably build a quartz thickness monitor easily
<azonenberg>
just open up a crystal oscillator and measure the output freq as the resonant element gets heavier from the deposited film
<diginet>
that might be difficult to calibrate
<diginet>
aren't piezos notorious for nonlinearities?
<azonenberg>
No idea
<azonenberg>
All i know is that this is apparently the industry standard method for measuring thickness
<diginet>
sure
<azonenberg>
If we can find something else i'm all for it
<azonenberg>
Another option is two electrodes separated by a glass plate
<azonenberg>
and measure resistance between them
<diginet>
(not trying to shoot you down, I'm just trying to do think of all options)
<azonenberg>
given known distance and area we can calculate sheet resistance
<diginet>
*/to/do
<diginet>
yeah
<azonenberg>
Which is IMO the more important variable to control
<azonenberg>
vs thickness
<azonenberg>
This of course only works for conductive films
<azonenberg>
not dielectrics
<diginet>
my favorite paper is on a using sol-gel CeO2 as a high-k
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<_Sync_>
diginet I regularily manage 10^-10mbar at home
<_Sync_>
azonenberg: using a crystal osc as a microbalance works perfectly well
<_Sync_>
and yes, they do suffer from nonlinearities but you can just change them often enough
<azonenberg>
_Sync_: that's what i was thinking
<azonenberg>
just open up a stock crystal osc
<azonenberg>
buy like a dozen from the same manufacturer, same lot number
<azonenberg>
calibrate them against a single reference TCXO
<_Sync_>
no
<_Sync_>
too much hassle :D
<azonenberg>
open it up, measure the base clock frequency
<azonenberg>
Deposit at a constant rate, measuring the frequency, for X time
<_Sync_>
you just measure the frequency at startup
<azonenberg>
When you're done, pull it off and measure the film thickness
<azonenberg>
using a SEM or something
<_Sync_>
again, too much hassle
<azonenberg>
Guess it depeneds on how muc haccuracy you need
<azonenberg>
If you know the dimensions of the resonant element, you might be able to just calculate how much mass was added by the shift in the frequnecy
<_Sync_>
yes, but for +-5% just going by density works
<azonenberg>
Makes sense
<azonenberg>
and like i said before, i dont care about film thickness so much as resistivity
<_Sync_>
our only crystal balance we run is in the gold coater
<_Sync_>
and we just go by eye on there
<_Sync_>
and I manage to make films with ~20nm thickness variation
<azonenberg>
nice
<_Sync_>
and I'd just use Al for contacts
<_Sync_>
or gold for that matter
* Speedevil
ponders time of fight mass spectrometry.
* Speedevil
is contemplating silly things regarding batteries.
<Speedevil>
Not fully understanding the chemistry when passing current through molten solutions of flourides = exciting!
<_Sync_>
protip: buy a used RGA
<_Sync_>
if you need to resolve under 200AMU that's your best bet
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