<azonenberg_work>
So i'd need that, $250 each for P and N type dopants
<azonenberg_work>
$250 for Silicafilm
<azonenberg_work>
Thats the min order (4 fl oz), if anyone wants to buy some subset of it off me feel free :P
<mrdata>
4 fl oz for $250?
<azonenberg_work>
Yes
<mrdata>
seems really expensive
<azonenberg_work>
thats what i was quoted before
<azonenberg_work>
And trace metal grade chems are rarely cheap
<azonenberg_work>
But you dont need nearly that much
<azonenberg_work>
bear in mind the 4 ounces of Tantalumfilm i got, well...
<azonenberg_work>
i've used maybe 2 ml of 250 :p
<azonenberg_work>
actually no
<azonenberg_work>
sub 1
<azonenberg_work>
So lets see - i already have PR
<azonenberg_work>
i can get TMAH and dopants
<azonenberg_work>
i'd need a furnace
<azonenberg_work>
i can evaporate aluminum
<azonenberg_work>
i can etch aluminum with HCl:H2O2
<azonenberg_work>
FEOL process needs something to align dopants to, so i'd probably put a sacrificial aluminum layer down and etch alignment crosshairs into it
<azonenberg_work>
Then spin coat N type dopant
<azonenberg_work>
Spin coat PR, HF etch to pattern the N diffusion
<azonenberg_work>
Backfill with Silicafilm, bake to diffuse dopant
<azonenberg_work>
Optionally repeat the process if I'm doing P+ diffusion anywhere (assuming P type wafers)
<berndj>
mrdata, a CO2 laser is at 10.6µm, so the smallest spot you could make would be of about the same order, if you had a very fast lens.  i think that's getting a bit coarse for what azonenberg_work wants to be able to do
<azonenberg_work>
berndj: Yeah
<azonenberg_work>
If i was going to do laser direct write litho i'd use UV
<azonenberg_work>
385nm or so
<azonenberg_work>
with a ~1um spot
<azonenberg_work>
Thats actually on the list of methods to research
<mrdata>
ok
<berndj>
lol, got a spare excimer laser lying around?
<azonenberg_work>
berndj: if i had one i'd be using it already
<mrdata>
checks his pockets
<azonenberg_work>
I'm thinking bluray actually
<mrdata>
sorry
<azonenberg_work>
diode laser
<berndj>
google "sam's laser faq" if MTI's prices are too steep
<azonenberg_work>
berndj: i'm aware of the site
<mrdata>
yeah, you can make a N2 laser ithink, from aluminum flashing and air
<berndj>
azonenberg_work, do you really need 1200C to grow oxide, or do you need that only if you want it to grow quickly enough that you don't do it overnight
<azonenberg_work>
but i doubt they can help me with my problem with MTI's prices
<azonenberg_work>
berndj: it's quadratic with temperature i think, up to a point
<azonenberg_work>
let me look up the equation
<berndj>
dunno... for someone as disciplined as you, you could probably pull off a DIY Ar/Kr laser
<azonenberg_work>
berndj: i dont need a lot of power
<azonenberg_work>
100 mJ/cm^2 or so
<azonenberg_work>
is the complete exposure dose
<berndj>
how much coherence do you need?
<azonenberg_work>
bearing in mind that my die is well under that
<azonenberg_work>
Zero
<azonenberg_work>
I need a focused spot that i can aim
<berndj>
oh :(
<azonenberg_work>
that is relatively monochromatic
<berndj>
otherwise i was about to suggest the N2 laser
<azonenberg_work>
This is basically going to be a raster scan
<azonenberg_work>
when i say zero, i mean i dont need coherence at all
<berndj>
if you're willing to sacrifice some power, maybe
<azonenberg_work>
But it has t obe narrow
<azonenberg_work>
The plan is basically to raster scan the laser across the die
<azonenberg_work>
a ~1mm field at ~5um resolution is 200x200 pixels
<azonenberg_work>
blankign as necessary
<azonenberg_work>
just like those cheap laser projectors people mak
<azonenberg_work>
except the die is a lot closer
<azonenberg_work>
and the theta tolerance is smaller
<berndj>
wait, are we talking ablation or PR exposure?
<azonenberg_work>
berndj: PR exposure
<azonenberg_work>
ablation needs waaaay ore
<azonenberg_work>
more*
<berndj>
ah, hence you need <400nm lines
<azonenberg_work>
energy
<azonenberg_work>
Yes
<azonenberg_work>
But the spot size can be large as i am making what might be a projection mask rather than a contact one
<azonenberg_work>
I'm not projecting onto the di
<azonenberg_work>
its a mask (metalized microscope slide)
<berndj>
OT: i cut a section through weld beads i ran yesterday, and i'd like to etch them somehow so i can see the various zones.  suggestions?  I have HCl and H2O2, could that work?
<berndj>
(it's a crappy weld, but i want pics for my blog)
<azonenberg_work>
What is the material
<berndj>
mild steel
<azonenberg_work>
and whats the goal, show grain boundaries?
<azonenberg_work>
First step is to polish it
<berndj>
not necessarily even that, just to show the differences where crystals are smaller vs where they are larger
<azonenberg_work>
Re oxide growth rate...
<berndj>
polish - to what degree?  i suppose having filed it flat isn't enough :)