<azonenberg_lab> About to try BOE etching of tantalum oxide
<azonenberg_lab> We'll see how well my resist handles it
<azonenberg_lab> Not well :P
<azonenberg_lab> Back to liftoff, there's still a few more experiments to try
<CIA-67> homecmos r103 | trunk/lithography-tests/labnotes/azonenberg_labnotes.txt | Today's lab notes
<bart416> azonenberg, you there?
<azonenberg_work> bart416: Back
<bart416> How would you etch acrylic?
<bart416> Well more specifically not really etch
<bart416> I was thinking of using photoresist to do something it's not designed for
<azonenberg_work> Just finished a high-vacuum evaporation run of some copper
<bart416> coat the acrylic sheet in photoresist
<azonenberg_work> on glass, silicon, and Ta2O5 coated silicon
<azonenberg_work> Evaporators are fun, i definitely want to get one of my own at some point
<bart416> expose the letters I want on it, remove the excess
<bart416> Heh
<bart416> Fun
<bart416> Pictures!
<azonenberg_work> Still at work, when i get back i'll do some litho tests on these guys
<bart416> And then paint it
<bart416> And then remove the photoresist that was developed obviously
<azonenberg_work> Interesting
<bart416> So only the letters are left
<bart416> But will it work?
<azonenberg_work> Acrylic is hard to etch because its a polymer
<azonenberg_work> and so is photoresist
<bart416> well it's technically not etching
<azonenberg_work> You'd need to use a hardmask
<bart416> I'm using spray paint
<azonenberg_work> Most spray paint contains acetone
<azonenberg_work> Which will eat photoresist instantly
<bart416> yeah, that's my worry
<azonenberg_work> Also, you cant strip resist with anything but acetone (which will remove paint)
<azonenberg_work> If you had vacuum deposition capability it'd be easy
<azonenberg_work> Evaporate copper over the plastic (assuming it was vacuum compatible)
<bart416> If it were the other way around I could make a stencil
<azonenberg_work> Pattern copper with photoresist
<azonenberg_work> Strip resist
<azonenberg_work> Paint
<bart416> But this is near impossible >_>
<azonenberg_work> And then strip copper with acid
<azonenberg_work> Thing is, you'd need a LOT of copper
<azonenberg_work> I dont think it would work well
<bart416> I don't have enough pure copper heh
<bart416> Could canibalise some copper tubing I pulled out of the ground during some construction work but that's about it
<Laurenceb_> another mad idea form me
<Laurenceb_> could you screen rpint using OS film?
<Laurenceb_> http://www.a2zcorp.us/store/Category.asp?Cguid={CCCB3CBA-6763-499A-8223-DDDBACB0C380}&Category=BuildingMaterials%3ACovering
<Laurenceb_> 500nm plastic film
<bart416> doubt it
<Laurenceb_> if you make the film thinner it should be possible to reduce feature size
<azonenberg_work> Back
<azonenberg_work> bart416: I evaporated about 1/2" of strands from a stranded wire lol
<azonenberg_work> OS film?
<azonenberg_work> Whats the plastic
<azonenberg_work> What eats it?
<Laurenceb_> i dont know
<Laurenceb_> i was just thinking, i can screen print ~0.1mm with solder stencils
<Laurenceb_> the limiting factor is the film is approximately that thickness
<Laurenceb_> so the solder paste tends to lift off with smaller features
<bart416> Thin films like that are rather fragile
<Laurenceb_> alignment and warp would be problematic
<bart416> They'll never survive screen printing
<Laurenceb_> i dont know - it works on rc indoor planes ok
<bart416> mechanical stress on one point or or over a surface are two very different things
<Laurenceb_> hmm some features are impossible to print, come to think of it
<bart416> azonenberg, has anybody ever tried making huge semiconductors?
<bart416> I mean 5mm scale junctions :P
<azonenberg_work> bart416: Jeri made transistors that were mm scale
<azonenberg_work> I'm trying to shrink her process to tens of microns
<azonenberg_work> iow by around 2 orders of magnitude
<bart416> silicon or just point contact?
<azonenberg_work> She's made full complimentary pair CMOS inverters
<azonenberg_work> two planar CMOS transistors in one die
<bart416> any link to that actually?
<azonenberg_work> google "jeri ellsworth transistor" or something and you'll find hundreds of hits
<azonenberg_work> That was actually the initial inspiration for this project
<azonenberg_work> Though i'm now shifting my focus more toward MEMS
<bart416> So to outdo the scale I'd have to grown my own damn silicon crystal
<bart416> Challenge accepted!
<bart416> *grow
<azonenberg_work> Or you can go from my process to 45nm
<azonenberg_work> Its about the same order of magnitude
<bart416> Meh, I'm already writing up a proposal for a bachelors thesis about atomic scale circuits :P
<bart416> It's probably going to rejected cause it's too complicated for a bachelors or masters
<azonenberg_work> lol
<azonenberg_work> Do your phd on it?
<bart416> I want to go into biomedical electronics
<Laurenceb_> heh thats what im doing my phd on
<Laurenceb_> its rather bullshitty
<bart416> Laurenceb, depends on what you're specifically doing it on ;)
<Laurenceb_> im looking at perfusion monitoring
<Laurenceb_> supposed ot be
<bart416> Now that sounds boring indeed
<Laurenceb_> lol
<Laurenceb_> well its an unsolved problem
<bart416> monitoring is an unsolved problem?
<bart416> I think I've seen some devices that do that
<Laurenceb_> yeah but it doesnt give absolute flow
<Laurenceb_> i was looking at thermal techniques
<Laurenceb_> flexible surface probe with heated disk and outer ring
<Laurenceb_> heat to ~1C above baseline surface temperature and time power_inner/power_outer
<bart416> Please don't start about such things
<Laurenceb_> gives you bloodflow irrespective of tissue conductivity
<Laurenceb_> heh
<bart416> You'll bore me to death
<Laurenceb_> unfortunately thats what my supervisor says
<bart416> Understandable
<Laurenceb_> i think he wants me to change to another topic
<Laurenceb_> but ive spent the last 6 months making swimming reflectance PPG monitors for olympic swimmers :/
<bart416> Also understandable
<Laurenceb_> ultra lame
<bart416> lol
<bart416> Well, you're not stealing my idea :P
<Laurenceb_> PPG with an accelerometer on the back - its based on a spin off companies device
<bart416> I doubt you have a clue on how to start with it anyway so I'm safe
<Laurenceb_> xscale based unit :S
<Laurenceb_> my supervisor is obsessed with using an accelerometer for adaptive noise cancelling to remove motion artifacts
<bart416> He's not the only one
<azonenberg_work> interesting
<Laurenceb_> bart416: you had the same idea?!
<bart416> No
<bart416> I saw somebody work on something similar in the college electronics lab couple of months ago
<bart416> Also saw somebody else attempt to build a device to measure membrane thickness on the fly
<Laurenceb_> ppg with an accelerometer?
<Laurenceb_> if so i can say its been done and do something actually useful
<Laurenceb_> XD
<Laurenceb_> at least my work involves something other than sitting at a pc running matlab all day for 3/4years
<Laurenceb_> like 99% of people seem to be doing
<bart416> I'm not sure what the exact goal was
<bart416> All I know is that they stole our accelerometer we needed for another project
<Laurenceb_> heh
<bart416> And in response we gave it some tesla coil time
<bart416> And put it back in its place
<Laurenceb_> that keeps happening to me, each day something seems to be raided from my shelves
<bart416> I wonder why it suddenly stopped working
<Laurenceb_> heh
<bart416> We addopted a new policy, lock it in a metal container (wood and plastic they'll just cut through) or solder it to a board
<bart416> And never use sockets
<Laurenceb_> i refuse to run matlab at all :P
<azonenberg_work> Lol
<Laurenceb_> when i was a physics undergrad i saw a grad student trying to simulate a tokamak in matlab
<azonenberg_work> o_O
<azonenberg_work> Bet it didnt go too well
<bart416> simulate a tokamak in matlab??? o_O
<Laurenceb_> i spent a while looking at NMR flowmeters, but it looks like the noise is too high
<Laurenceb_> that would have been fun to try and build
<Laurenceb_> so yeah my next meeting with supervisor will probably involve a change of research topic
<bart416> You know, trying to remove the noise would be a nice subject
<Laurenceb_> nmr mouse.de or something
<azonenberg_work> You want to use NMR for what?
<Laurenceb_> flowmetery