Hi So, although those look pretty affordable, I'm rather looking for something with which I can use a bit more complex recipes in the future, so that I might actually become able to run an entire CMOS process with silicide, grow nitride layers and build my own flash memory at some point. So I keep checking out eBay and I'm also trying to get an offer below 1000 USD from an Israeli firm, but it looks bad... :-/ Which however is no wonder, because their furnace is VERY advanced.
Cheers -lev
On Monday, April 12, 2021 9:50:46 PM WEST Martin Geisse wrote:
Hi David,
thanks for the hint about carbon, didn't know that. That the furnace is top-loading is something I just overlooked. However, the same company has front-loading furnaces and it seems that with the Quikmelt, only the crucible is made out of graphite, the furnace itself doesn't seem to have any. (To be more exact, the description of the Quikmelt says something about organic binder and I'm not sure if that leaks any carbon; the description of the Rapidfire doesn't say anything like that but the material looks similar).
https://www.tabletopfurnace.com/product/rapidfire-pro-l/ https://www.tabletopfurnace.com/product/rapidfire-pro-lp/
The -LP variant has more sophisticated temperature control.
There is another thing that came to my mind about the furnace though: Do they have to be airtight, or placed inside an airtight container, for the doping steps? IIRC doping has to happen under nitrogen or nitrogen/hydrogen atmosphere (or even vacuum) so it doesn't accidentally grow oxide on the silicon.
Greetings, Martin
On Mon, Apr 12, 2021 at 4:27 PM David Lanzendörfer <
leviathan@libresilicon.com> wrote:
Hi There's a problem... It's for vertical loading and the carbon will contaminate the circuit. I know those furnaces well, it's used in recycling Aluminum and for casting. I wanna make a "Liberator" (3D printed gun) into metal using one of those already for a while. However, those furnaces are unsuitable for chip making I'm afraid.
Cheers -lev
On Monday, April 12, 2021 10:49:52 AM WEST Martin Geisse wrote:
Hi,
so here's some more thoughts about the glove box:
- furnace
I found this mini furnace manufacturer: https://www.tabletopfurnace.com/
They are somewhat outside our price range, about $500, but otherwise they match quite well, e.g.
https://www.tabletopfurnace.com/product/quikmelt-10/
That furnace is electrically powered (you probably shouldn't use a
propane
furnace indoors), it's tiny so less heat is wasted, and due to its size
it
should be possible to attach it to the back side of the glove box. I
still
think that having the furnace inside the box is a problem because the
heat
cannot escape well, but having it outside and connecting it through
another
opening in the box should be possible.
- insulation
You'll still probably have to thermically insulate the furnace from the glove box (even if the back wall is made of sheet metal and not acrylic). My first idea is to use calcium silicate boards, e.g.
https://www.promat.com/en/industry/technologies/calcium-silicates/high-tem pe>
rature-insulation/
These boards are used to insulate masonry heaters from walls and can take up to 1000°C -- the outside of the furnace is probably not as hot, so
that
should be enough. My guess is to use high-temperature mortar to glue the boards to the furnace (keeping the inside dust-free, it's a clean room after all) and something more flexible, e.g. high-temperature silicone,
to
glue the boards to the back side of the glove box. If both connections
were
rigid then it would break too easily, especially with thermal expansion.
The alternative would be rock wool, but that stuff is nasty (at least if it's similar to glass wool). Calcium silicate is similar to gypsum in handling, just more expensive.
- spin coater
My first idea to make this cheap is an axle connected to a disk and
mounted
in such a way that the axle can spin but not tilt. You could then attach
a
handheld drill to the bottom of the axle to spin it.I still like the idea except that the disk has to be inside the glove box and the axle has to leave the box at the bottom, so keeping it dust-tight AND freely
spinnable
but not tiltable is the main challenge with that. Someone who is wiser in mechanics can probably do that easily.
Greetings, Martin
On Sun, Apr 11, 2021 at 12:24 PM David Lanzendörfer <
leviathan@libresilicon.com> wrote:
Hi Maybe you can join today 6pm UTC on our Mumble server murmur.libresilicon.com and we can discuss where to best place the airlock and how to build it
the
easiest and cheapest way?
Cheers -lev
On Sunday, April 11, 2021 8:17:01 AM WEST Martin Geisse wrote:
Hi David,
some ideas / questions:
I was thinking about using sheet metal for everything
Pardon my ignorance, but how are you going to see what you are doing
in
there? Did you mean that one side is still acrylic? Front or top?
airlock
If this is on the side wall, then it is probably hard to reach with
your
hands. On the other hand, the back wall (opposite of the gloves) is
the
most precious space you have and "wasting" it for the airlock is not good either...
A quick idea would be to attach the airlock at the bottom, with the outer door facing towards you and the inner door being a "trap door" in the bottom of the box.
tools
If everything happens inside the box, space is even more precious. You'll need storage for the materials and chemicals, illumination stage, hot plate, spin coater, furnace, ... A rotating shelf on the back side
might
be
a solution for that.
OTOH, an unsolved problem is be what the residual heat of the
furnace is
going to do to the acrylic box...
gloves
Gloves always bring the danger of trapping hazardous chemicals
*inside*,
right next to your hands. You'll probably need a material that withstands *all* of those chemicals, otherwise you might have the piranha etch
make
the gloves porous and then HF leak through them... A simple warning
not
to
spill anything over the gloves is probably not enough because these
things
just happen anyway.
Greetings, Martin
On Sat, Apr 10, 2021 at 11:33 PM David Lanzendörfer <
leviathan@libresilicon.com> wrote:
Hi I was thinking about using sheet metal for everything which doesn't
need
to be transparent (even cheaper than acrylic glas). For the airlock I was figuring I could do a cut out like in the
attached
screen and fold it, then either weld or screw an aluminum box made from folded sheet metal as well.
What do you think?
Cheers -lev_______________________________________________ Libresilicon-developers mailing list Libresilicon-developers@list.libresilicon.com
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