#homecmos IRC log for Saturday, 2011-10-22

soul-dk done reading for today :)  i  conculde that e-readers at least this (sony prs-t1) is close to what these devices should do  few quirks in software (and ofcourse some type of sony usb cable thingy)  but reading is alot better then from lcd00:02
azonenbergSo... I've already  demonstrated the ~100um resolution i'm looking for on PCBs so it should be no problem to get it on silicon for dicing00:29
azonenbergTime to print some masks00:30
CIA-67homecmos r148 | trunk/lithography-tests/labnotes/azonenberg_labnotes.txt | Today's lab notes02:28
azonenbergSlow progress with classes and everything02:45
azonenbergBut work is progressing02:45
Helldeskhow do you make the masks?04:13
azonenbergHelldesk: Laser printer and transparency film from staples04:14
azonenbergThese are contact masks, 1:1 scale04:14
azonenbergso i'm limited to 600dpi04:14
azonenbergprojection masks get much higher resolution since i reduce optically04:15
azonenbergbut the cost is that i can no longer do a whole wafer in one exposure04:15
azonenbergalmost done with a cross section rendernig of the comb drive process04:25
azonenbergok, model is taking longer to design than anticipated06:25
bart416auch azonenberg07:30
azonenbergProcess outline coming in a few mins07:32
azonenbergputting the final touches on it now07:32
Action: azonenberg crops a few dozen screenshots08:01
azonenberglekernel: http://imgur.com/a/kxARq08:20
azonenbergAny thoughts on the process?08:24
azonenbergWafer is at step 2 right now08:24
soul-dwell it made it more clear for me08:24
azonenberg3-5 are scheduled for tuesday08:24
azonenbergwhen i can get time on the evaporator08:24
azonenbergAfter the 400um KOH etch, the dies are separate08:25
soul-dyou  use  university  tools ?08:25
azonenbergand all future lithography is done on the projection rig one at a time08:25
azonenbergThe evaporator is the one thing i dont have at home yet08:25
bart416You should have written the description of the process in VHDL...08:25
azonenbergAs well as the SEM i use for when my optical scope isnt good enough08:25
azonenbergsoul-d: and thats exactly what it was intended to be for08:26
azonenbergTo make the process more understandable08:26
azonenbergi'm going to try and make a little presentation (poster or slideshow TBD) when i get further on in the process08:26
soul-dok so those  things are just  for  the moment not that they  are imposible to do at home ?08:26
bart416Wren't you looking into sputtering?08:27
azonenbergIncluding in-process SEM images08:27
azonenbergand optical08:27
azonenbergbart416: I am exploring both sputtering and evaporation08:27
azonenbergBoth are within the realm of possibility for a dedicated hobbyist08:27
bart416soul-d, building a high enough resolution SEM at home is tricky at the best of times08:27
azonenbergThe SEM is not strictly necessary08:27
bart416It's a design project on its own08:27
azonenbergi could do everything i did with an optical scope08:27
bart416It'd take well over a year to get something that'll perform good enough08:27
azonenbergbut the sem is there and it helps me sanity-check things08:27
bart416And then you need to develop all the specialised equipment to surround it and the right detectors08:28
azonenbergbart416: everhart-thornley detector shouldnt be too tough to build08:28
azonenbergcontrol would be all DSP08:28
azonenbergmake no doubt about it, i intend to build one some day08:28
azonenbergBut its a lower priority08:28
azonenbergsoul-d: Evaporation is pretty simple conceptually08:29
bart416With an everhart-thornley detector you're not going to get very good results though08:29
soul-dcurrently reading books  more on fpga  though  found one that also treats  the lower level  a bit more08:29
azonenbergbart416: but it'd be good for starters08:29
bart416And you won't get many of the other advantages of a SEM08:29
azonenbergsoul-d: Stick a tungsten filament between two electrodes08:29
azonenbergcoil copper wire around it08:29
azonenbergstick your sample underneath08:29
azonenbergput a bell jar on top, suck out the air08:29
soul-djust  wondering how truly homecmos it  would  be08:29
azonenbergrun current through filament, it heats up08:29
azonenbergmetal evaporates08:29
azonenbergsoul-d: The evaporation is the one process i dont do at home08:30
soul-dyeah i think i read on it for making   mirros for08:30
azonenbergand as soon as i can afford a vacuum pump, i'll do it08:30
azonenbergsame process08:30
soul-dyou just have sticky and no sticky layers on wafer ?08:30
azonenbergwhat do you mean sticky08:30
soul-degg plases you want depost08:30
soul-dand stuff you protect08:30
azonenbergEvaporated films will stick to anything in a straight line from the source08:31
azonenbergso you can cast shadows in the film with photoresist etc08:31
azonenbergYou can also put resist over the film and etch through holes in the resist08:31
azonenbergi use both techniques in this process08:31
azonenbergGenerally speaking, all microfab processes are in one of two broad classes08:33
azonenbergadditive and subtractive08:33
soul-dk yeah makes more sense  now then yesterday  ;)08:33
azonenbergEvaporation is an additive process, so is spin coating08:33
azonenbergetching is subtractive08:34
azonenbergIn this case i am patterning the bottom Cr by both08:34
azonenbergi deposit everywhere that i want it from time zero08:34
azonenbergetch the silicon a bit08:34
azonenbergthen remove part of the remaining Cr08:34
soul-dyeah intresting stuff  how did you start i mean doubt you jumped  to these sizes  or technology08:47
bart416azonenberg, I think soul-d doesn't know about trial and error :P09:44
azonenbergbart416: actually?18:20
azonenberg20um was my first attempt at going smaller than the 150-200um design rule i had before18:20
azonenbergthat was contact lithography on printed circuit board18:21
azonenbergi just threw a 10x objective in between18:21
bart416Sounds like trial and error to me :P18:22
azonenbergbart416: Lol18:23
azonenbergIt pretty much was18:23
azonenbergJust saying, i didnt slowly and painfully work my way down from 20018:24
azonenbergHowever, 20 has been a bit of a brick wall in that i'm having trouble shrinking using techniques i've tried so far18:24
azonenbergi hit 5 a few times but cant do it reliably18:24
bart416Have you tried changing light source to something more uniform?18:43
bart416What wavelength is ideal?18:44
azonenbergDepends on the resist18:44
azonenbergMine is 405nm peak sensitivity18:44
bart416405nm, lets see if I have any lasers for that18:44
azonenbergI'm now using a fiber optic illuminator (wideband halogen source)18:44
azonenbergProblem is, the beam is a little small18:45
azonenbergi need to build a condenser to widen the beam18:45
azonenbergAnything from 365-405 will work18:45
azonenbergmaybe even up to 450ish18:45
bart416how wide do you need?18:46
azonenbergthat's mercury vapor G through I line18:46
azonenbergAbout 2cm18:46
azonenbergthats the diameter of the camera port on top of the scope that i put the mask18:46
azonenbergi need a relatively collimated beam of that diameter18:46
bart4162cm, that'll be hard18:47
azonenbergand as uniform as possible18:47
azonenbergtop-hat distribution ideally18:47
bart416Well, the issue is you'd be widening the beam a lot18:48
bart416It'd lose its intensity advantage18:48
azonenbergI can handle a slightly longer exposure, right now i have about a ~1cm disk at the end of my fiber bundle18:48
bart416Only UV laser I have is in my own photoresist setup18:50
Action: azonenberg doesnt have any lasers18:51
azonenbergexcept for ~760nm 1-5 mW diodes18:51
azonenbergbut those dont really count for lithography18:51
bart416Also, blu ray laser18:52
bart416Its perfect18:52
bart416It's exact 405nm18:52
azonenbergYeah, i agree18:52
azonenbergBut if i was using one it'd be for direct write18:53
azonenbergin a much narrow beam18:53
bart416http://www.dealextreme.com/p/100mw-405nm-blue-violet-royal-purple-laser-module-3v-80923 looks nice18:53
azonenbergprobably with nanosecond-level pulses18:53
bart416I tried pulsed lasers before18:54
bart416I found them unsuitable for PCB exposure18:55
azonenbergYou misunderstand18:55
azonenbergi'd do short pulses on the bluray diode for direct write18:55
bart416I doubt they'll do better at smale scale18:55
azonenbergbecause each pixel is so small i dont need a lot of energy18:55
azonenbergbasically, figure out how much energy each pixel needs to get exposed completely18:55
azonenbergand differentiate18:55
bart416Well, the issue I found is actually the shape of the beam18:56
azonenberghow so?18:56
bart416Round beam, square pixels18:56
azonenbergI'd want a ~5um round beam18:56
azonenberg20um square pixels with rounded corners18:56
bart416You'd need significant overlap I think18:57
azonenbergso for a 20um line i do 5um shots centered at 0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 2018:57
azonenbergassumption is that the desired tophat beam will actually be a little more gaussian18:58
berndjis a laser diode's light sufficiently collimated for lithography?19:19
berndji thought that mattered19:20
azonenbergberndj: You'd need optics19:21
azonenbergBut you need optics even more with a halogen lamp :p19:21
berndjoptics can't collimate a beam without losing some of the light19:21
berndj(imprecise jargon)19:22
azonenbergberndj: yes, i know19:22
azonenbergThats why you get a nice high power source19:22
azonenbergso you can afford to lose some19:22
berndjah ok19:22
berndjis a bluray LD a "nice high power source"?19:22
azonenberg200 mJ/cm^2 is what i need19:22
azonenbergmy die is maybe 1/4 cm^2 (5mm square) at most19:22
azonenbergos i need 50 mJ over the entire die19:22
azonenbergDelivered over several minutes by a moving laser head19:23
azonenbergone milliwatt of actual energy after optics is probably enough19:23
azonenbergbluray diode is a few hundred i think19:23
azonenbergi'll probably have to pulse it to get average intensity down low enough to not overexpose19:23
CIA-67homecmos r149 | trunk/papers/ (17 files in 3 dirs) | Added first draft of project poster19:31
soul-ddon't you need to move the laser realy precise with that method19:50
azonenbergsoul-d: yes, or reflect it off precisely aimed mirrors19:50
azonenbergBut it would let me get better resolution than i can with a normal printer19:50
azonenbergthats the whole point19:50
soul-dhow did you start btw on what size  since you mention printer ? you should make entry howto  or proof of concepts ... maybe browse  site19:57
azonenbergsoul-d: I'm actually doing a poster providing a summary of what's going on now19:58
soul-ddin't even knew you had nyano technology :)19:58
azonenberghoping to present at the CDMMS (capital district microscopy and microanalysis socity) meeting next month19:58
azonenbergthey have their anual microanalysis and materials science poster competition19:58
soul-doh yeah was looking at microscope alwasy wanted one   but i usaly start looking and by time im done  i need 10K +19:59
azonenbergeven in the (very likely) event i do not win best poster, it should help increase awareness of the project19:59
azonenbergand mine was $1.2k including the camera19:59
soul-dyeah found a site with ocassions19:59
soul-dbut still pricy19:59
azonenbergamscope.com is where i got this one19:59
azonenbergNot the greatest scope, i am definitely seeing limitations19:59
soul-dnetherlands here so stuck to looking local20:00
azonenbergBut i could also afford it20:00
azonenbergAh, i see20:00
soul-dim verry intrested  thats why i asked is this where digital meets chemistry :)20:01
soul-dand other fun stuff20:01
soul-dyou have a list of intresting books ?   currently reading bit out of  "digital systems design with fpga"  wich starts a bit talking on the technology's behind it  but still different avenue20:04
azonenbergI've been doing most of my learning online actually20:05
soul-dk yeah din't fix wifi yet  here  so cant use ereader online  :P  thats why documents still preferred20:08
soul-drealy  like the e-ink stuff20:08
soul-dinteresting at least  would be to figure out if  one in eu  / netherlands has acces to chemicals needed20:24
soul-dcause if you are i assume usa  based ?20:24
azonenbergYes, i am20:25
azonenbergBut most of the materials i've been using are not hard to get hold of20:25
azonenbergHCl, NaOH20:25
azonenbergDistilled water, acetone20:25
azonenbergthe trickiest one is photoresist20:25
azonenbergoh, and hydrogen peroxide (3% aka drugstore grade)20:26
soul-dgot those  is it the same as for pcb ?20:26
azonenbergthe resist?20:26
azonenbergI am using liquid resist sold for PCBs20:26
azonenbergI dilute it 50% with acetone to reduce the viscosity and thin the layer20:26
azonenbergthen spin coat20:26
soul-di think a shop in uk sold it to  in a brush type thingy20:26
soul-dor marker20:26
azonenbergThat wont work, you need to be able to do an even film20:27
azonenbergMine is sold as a liquid20:27
azonenbergapparently its made in a spray can too, which is less good but if you spray it on and then spin coat you can probably get it nice and even20:27
soul-dyeah i assumed it's a liquid inside ?  and just  tip to dispersi it evenly20:27
CIA-67homecmos r150 | trunk/papers/003_Poster/Poster.odp | Continued work on poster21:27
azonenbergAnyone have comments?23:20
azonenbergPresenting an updated version of this (need to finish the references and add pics from my experiments being conducted this coming week) next month23:21
soul-dwhat is thecnical grade HCL  egg % ?23:25
azonenbergsoul-d: Good point23:25
azonenbergI need to shrink the text down by a bit, there's a little much23:26
azonenbergand font should be larger23:26
azonenbergFor scale this will be printed on a 3x4 foot poster23:26
soul-dyeah   same  for the KOH also % missing but i think you can get that at 99,9% ?23:27
azonenbergThe KOH is powder23:27
azonenbergso almost pure23:27
soul-dyeah  draining cleaner stuff i think oposite of naoh23:27
azonenbergthere may be some impurities but its not like a dilute solution23:27
azonenbergThis was relatively high grade23:27
soul-dyeah got a labstore online you can order23:28
azonenbergturns out this is actually food grade23:28
soul-dalso found a "garden" shop wich sells most chemicals23:28
soul-dwould be first place for me to look for chems23:31
azonenbergYeah, thats why mems is easier than cmos23:31
azonenbergcmos is much more sensitive to trace metal impurities23:32
azonenbergi am seriously skeptical as to how much i could do cmos wise without buying "real" trace metal grade supplies23:32
soul-dok so for cmos youd be bussy purifing resources or buying :P23:32
azonenbergbipolar transistors might be a little less sensitive23:32
azonenbergi have to read up more on BJTs23:32
soul-di like your spin coater makes it  more home doable already :P  understood more of the alliance programs i already had on system tried to install  glade but need fresh linux install again23:34
soul-dit worked  but it also crashed a bit donno how realiable it is :)23:35
azonenbergYes, its not very reliable23:35
azonenbergI use it because i havent had the time to learn any package that's more open and reliable23:35
azonenbergBut as long as i  can export my design to GDS23:35
azonenbergi can open it up in another tool23:35
soul-di think i had that mentor grapics progam somehwere around23:38
soul-dbut definetly not open23:38
soul-di always download packages that are expensive just for fun :)23:38
soul-dmight come in ahndy some day :)23:38
soul-dwoulnd know where it is  though :)23:40
soul-dbut you can't write it in vhdl ?23:40
soul-dor hdl language ?23:41
azonenbergYou can do that for digital circuits but you still have to design the cell library23:41
azonenbergand compile your design to cells + wiring23:41
soul-dso comb drive is just cause of the pattern  but what does it do ?23:57
azonenbergsoul-d: it's pretty much the mems equivalent of a solenoid23:58
azonenbergwas chosen as the first actual device to build because its relatively simple23:58
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