#homecmos IRC log for Thursday, 2011-07-21

azonenberg_labAbout to try BOE etching of tantalum oxide02:18
azonenberg_labWe'll see how well my resist handles it02:18
azonenberg_labNot well :P02:54
azonenberg_labBack to liftoff, there's still a few more experiments to try02:54
CIA-67homecmos r103 | trunk/lithography-tests/labnotes/azonenberg_labnotes.txt | Today's lab notes03:27
bart416azonenberg, you there?16:35
azonenberg_workbart416: Back19:32
bart416How would you etch acrylic?19:33
bart416Well more specifically not really etch19:33
bart416I was thinking of using photoresist to do something it's not designed for19:33
azonenberg_workJust finished a high-vacuum evaporation run of some copper19:33
bart416coat the acrylic sheet in photoresist19:33
azonenberg_workon glass, silicon, and Ta2O5 coated silicon19:33
azonenberg_workEvaporators are fun, i definitely want to get one of my own at some point19:33
bart416expose the letters I want on it, remove the excess19:33
azonenberg_workStill at work, when i get back i'll do some litho tests on these guys19:34
bart416And then paint it19:34
bart416And then remove the photoresist that was developed obviously19:34
bart416So only the letters are left19:34
bart416But will it work?19:34
azonenberg_workAcrylic is hard to etch because its a polymer19:34
azonenberg_workand so is photoresist19:34
bart416well it's technically not etching19:34
azonenberg_workYou'd need to use a hardmask19:34
bart416I'm using spray paint19:35
azonenberg_workMost spray paint contains acetone19:35
azonenberg_workWhich will eat photoresist instantly19:35
bart416yeah, that's my worry19:35
azonenberg_workAlso, you cant strip resist with anything but acetone (which will remove paint)19:35
azonenberg_workIf you had vacuum deposition capability it'd be easy19:35
azonenberg_workEvaporate copper over the plastic (assuming it was vacuum compatible)19:35
bart416If it were the other way around I could make a stencil19:36
azonenberg_workPattern copper with photoresist19:36
azonenberg_workStrip resist19:36
bart416But this is near impossible >_>19:36
azonenberg_workAnd then strip copper with acid19:36
azonenberg_workThing is, you'd need a LOT of copper19:36
azonenberg_workI dont think it would work well19:36
bart416I don't have enough pure copper heh19:36
bart416Could canibalise some copper tubing I pulled out of the ground during some construction work but that's about it19:37
Laurenceb_another mad idea form me19:38
Laurenceb_could you screen rpint using OS film?19:38
Laurenceb_500nm plastic film19:44
bart416doubt it20:03
Laurenceb_if you make the film thinner it should be possible to reduce feature size20:14
azonenberg_workbart416: I evaporated about 1/2" of strands from a stranded wire lol20:17
azonenberg_workOS film?20:17
azonenberg_workWhats the plastic20:17
azonenberg_workWhat eats it?20:17
Laurenceb_i dont know20:20
Laurenceb_i was just thinking, i can screen print ~0.1mm with solder stencils20:21
Laurenceb_the limiting factor is the film is approximately that thickness20:21
Laurenceb_so the solder paste tends to lift off with smaller features20:21
bart416Thin films like that are rather fragile20:22
Laurenceb_alignment and warp would be problematic20:22
bart416They'll never survive screen printing20:22
Laurenceb_i dont know - it works on rc indoor planes ok20:22
bart416mechanical stress on one point or or over a surface are two very different things20:23
Laurenceb_hmm some features are impossible to print, come to think of it20:23
bart416azonenberg, has anybody ever tried making huge semiconductors?20:24
bart416I mean 5mm scale junctions :P20:24
azonenberg_workbart416: Jeri made transistors that were mm scale20:24
azonenberg_workI'm trying to shrink her process to tens of microns20:24
azonenberg_workiow by around 2 orders of magnitude20:24
bart416silicon or just point contact?20:25
azonenberg_workShe's made full complimentary pair CMOS inverters20:25
azonenberg_worktwo planar CMOS transistors in one die20:25
bart416any link to that actually?20:25
azonenberg_workgoogle "jeri ellsworth transistor" or something and you'll find hundreds of hits20:26
azonenberg_workThat was actually the initial inspiration for this project20:26
azonenberg_workThough i'm now shifting my focus more toward MEMS20:26
bart416So to outdo the scale I'd have to grown my own damn silicon crystal20:28
bart416Challenge accepted!20:28
azonenberg_workOr you can go from my process to 45nm20:29
azonenberg_workIts about the same order of magnitude20:29
bart416Meh, I'm already writing up a proposal for a bachelors thesis about atomic scale circuits :P20:31
bart416It's probably going to rejected cause it's too complicated for a bachelors or masters20:33
azonenberg_workDo your phd on it?20:37
bart416I want to go into biomedical electronics20:42
Laurenceb_heh thats what im doing my phd on20:42
Laurenceb_its rather bullshitty20:42
bart416Laurenceb, depends on what you're specifically doing it on ;)20:44
Laurenceb_im looking at perfusion monitoring20:44
Laurenceb_supposed ot be20:44
bart416Now that sounds boring indeed20:44
Laurenceb_well its an unsolved problem20:44
bart416monitoring is an unsolved problem?20:45
bart416I think I've seen some devices that do that20:46
Laurenceb_yeah but it doesnt give absolute flow20:46
Laurenceb_i was looking at thermal techniques20:47
Laurenceb_flexible surface probe with heated disk and outer ring20:47
Laurenceb_heat to ~1C above baseline surface temperature and time power_inner/power_outer20:48
bart416Please don't start about such things20:48
Laurenceb_gives you bloodflow irrespective of tissue conductivity20:48
bart416You'll bore me to death20:48
Laurenceb_unfortunately thats what my supervisor says20:48
Laurenceb_i think he wants me to change to another topic20:51
Laurenceb_but ive spent the last 6 months making swimming reflectance PPG monitors for olympic swimmers :/20:51
bart416Also understandable20:51
Laurenceb_ultra lame20:51
bart416Well, you're not stealing my idea :P20:52
Laurenceb_PPG with an accelerometer on the back - its based on a spin off companies device20:52
bart416I doubt you have a clue on how to start with it anyway so I'm safe20:52
Laurenceb_xscale based unit :S20:52
Laurenceb_my supervisor is obsessed with using an accelerometer for adaptive noise cancelling to remove motion artifacts20:53
bart416He's not the only one20:54
Laurenceb_bart416: you had the same idea?!20:57
bart416I saw somebody work on something similar in the college electronics lab couple of months ago20:58
bart416Also saw somebody else attempt to build a device to measure membrane thickness on the fly20:58
Laurenceb_ppg with an accelerometer?20:59
Laurenceb_if so i can say its been done and do something actually useful21:02
Laurenceb_at least my work involves something other than sitting at a pc running matlab all day for 3/4years21:03
Laurenceb_like 99% of people seem to be doing21:03
bart416I'm not sure what the exact goal was21:04
bart416All I know is that they stole our accelerometer we needed for another project21:04
bart416And in response we gave it some tesla coil time21:04
bart416And put it back in its place21:04
Laurenceb_that keeps happening to me, each day something seems to be raided from my shelves21:04
bart416I wonder why it suddenly stopped working21:05
bart416We addopted a new policy, lock it in a metal container (wood and plastic they'll just cut through) or solder it to a board21:05
bart416And never use sockets21:05
Laurenceb_i refuse to run matlab at all :P21:05
Laurenceb_when i was a physics undergrad i saw a grad student trying to simulate a tokamak in matlab21:07
azonenberg_workBet it didnt go too well21:07
bart416simulate a tokamak in matlab??? o_O21:07
Laurenceb_i spent a while looking at NMR flowmeters, but it looks like the noise is too high21:10
Laurenceb_that would have been fun to try and build21:10
Laurenceb_so yeah my next meeting with supervisor will probably involve a change of research topic21:18
bart416You know, trying to remove the noise would be a nice subject21:21
Laurenceb_nmr mouse.de or something21:22
azonenberg_workYou want to use NMR for what?21:22
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