#homecmos IRC log for Thursday, 2011-09-15

swkhanhello =)01:53
berndjazonenberg, some possibly useful info: http://www.microchemicals.eu/technical_information/  (i see the word "chromium" for example)02:00
azonenbergberndj: i already raed that lol08:27
B0101hi azonenberg11:05
azonenbergJust did some tests of using evaporated Cu over Cr as a wet etch mask for KOH11:06
azonenbergThe Si didnt etch at all11:06
azonenbergeven though the metal was removed11:06
azonenbergI think that the Cu was removed but the ~5nm of Cr (too thin to see) is still there masking the KOH11:06
azonenbergGoing to try repeating the process with a longer HCl etch to make sure the Cr is gone11:06
B0101oh. and I have found the supplier i was talking about last week11:07
B0101I now got to wait for the wafers to arrive...11:08
azonenbergyou actually ordered some?11:09
azonenbergWhat type11:09
CIA-67homecmos r121 | trunk/lithography-tests/labnotes/azonenberg_labnotes.txt | Today's lab notes11:09
B0101azonenberg: p-type wafers, orientation: 10011:10
azonenbergsingle polish? 4-inch?11:10
B0101single polish at 2 inch11:11
B0101I wonder if my furnace still works though....11:12
azonenbergTime to find out lol11:14
azonenbergOxidation is a capability I want but dont have yet11:14
azonenbergi have a toaster oven (goes a little hotter but worse control) for reflow soldering11:14
azonenbergand a nice lab oven11:14
azonenbergbut they max out at 260 and 225C respectively11:14
azonenbergthen a hot plate11:15
B0101I think i will need Si 29...11:16
B0101Or silicon isotope 2911:16
azonenbergWhy is that?11:17
azonenbergwhat does the isotope matter to you11:17
azonenbergI assume you are trying to build electronics and not a nuclear device :p11:17
B0101azonenberg: I need silicon isotope 29 because of its 1/2 nuclear spin.11:18
B0101for an experimental Josephson Junction11:18
azonenbergi dont know enough about them to be able to say much11:18
azonenbergall of my work to date has been MEMS based11:19
azonenbergfocusing on the mechanics of patterning11:19
B0101I'm gonna be afk, talk to you in a while11:20
B0101i'm back11:29
azonenbergthat was fast lol11:30
B0101just went get the door, and found that my 100+ BC547 transistors have arrived11:32
B0101you can guess what they're for11:33
Action: azonenberg is working on database homework due in a few hours11:33
azonenbergand i dont know the model11:33
azonenbergdont even know if they're fets or bjt11:34
B0101the bc547 are BJTs11:39
azonenbergSo what are you using them on?11:42
B0101I am using some to repair a board11:45
B0101and the rest for a homemade CPU11:45
B0101of course, it will be very slow11:45
bart416azonenberg, I just managed to extract the electron cannon from the crt's glass tube without damaging13:24
swkhanazonenberg: you're still working on the copper stuff? =)16:13
swkhanever figure out why chromium works?16:13
swkhanor why titanium is used as an adhesion layer for platinum, etc.?16:13
bart416swkhan, learn some basic chemistry16:47
swkhanbart416: ouch =( i read a book on chemistry, i still don't understand. transitional metals are weird16:47
bart416You need to look at the oxidation states in specific16:48
bart416That's the easy guideline16:56
bart416On the other hand, you need to look at the potential differences for the redox reaction16:56
bart416And the molecular orbitals16:56
bart416But to show it easy: Platinum has two common oxidation states 4 and 2 and uncommonly 6 and 3, while Titanium has 4, 3, 2; chrome has 6, 4, 3, 216:58
bart416azonenberg, about that railgun design17:34
bart416We did some more math17:34
bart416We figured out if we actually built it like we originally intended to it would have fired17:34
bart416It'd rip itself apart (in a cloud of shrapnell I think)17:34
azonenberg_workhi mrdata18:38
bart416I heard captain picard was still looking for you!18:43
mrdatayes, ever since that incident on romulus18:43
mrdatabut, he'll have to wait18:43
bart416Strictly speaking the incident wasn't on romulus18:44
bart416But related to romulans, your memory banks are flawed!18:44
mrdataan unfortunate consequence of the explosion18:44
bart416I blame listening to trekies whining about irc trolls for knowing such things :|18:44
mrdataand now to business. so this is the first ive heard of #homecmos18:46
mrdatawhat goes on, around here?18:46
azonenberg_workmrdata: we've been around for a while but are still small18:46
azonenberg_workAs of now i'm the main one doing lab work but am getting good input from others18:46
azonenberg_workB010101 isnt here right now18:46
azonenberg_workbut is setting up a lab as well18:46
azonenberg_workshe's planning to do work on Josephson junction stuff from what i hear18:46
azonenberg_worki'm focusing on MEMS18:46
azonenberg_workand am the main one backing the project18:47
Action: mrdata wants sketchy homebrew mems sensor devices18:47
mrdatajust to scare people18:47
azonenberg_workmrdata: Once i get a working comb drive18:47
azonenberg_worka mems accelerometer is within reach18:47
azonenberg_workthe control stuff will obviously be an external microcontroller and not a stacked-die design like modern ones are18:48
azonenberg_workAnd bonding is still an unsolved problem18:48
bart416mrdata, you building an icbm?18:48
azonenberg_workright now i am focusing on fab, and i have a probing station suitable for testing a couple of points18:48
azonenberg_workthree probes is enough to do a single transistor18:48
azonenberg_workwill need four or five to test gates, unless i hard-wire inputs to Vdd or Vss18:48
mrdatabart416, not building, no; i am curious about what-if scenarios, for global disaster and collapse18:49
azonenberg_workmrdata: a lot of people are18:49
azonenberg_workOne thing none of us have touched on is the materials18:49
mrdataso it would be nice to have, let's see.. homebrew hall effect sensor, temperature sensor,...18:49
bart416After I'm done there'll be no globe left for a global disaster18:49
azonenberg_workphotoresist, for example, i have no idea how to make18:50
mrdatasilicon purification18:50
azonenberg_worki know the theory behind crystal growth but have no idea how to refine the materials18:50
azonenberg_workIts not something i'd attempt with the setup i have now18:50
Action: mrdata has read up on solar grade silicon purification techniques18:50
mrdatabut i havent done any18:50
azonenberg_workHaving a Czochralski rig in my basement would be cool18:50
azonenberg_workMake my own 4-inch boules lol18:51
azonenberg_workBut i'm not nearly that advanced yet18:51
azonenberg_workbart416: oh, good news18:51
Action: mrdata would like to have a x-ray photovoltaic cell18:51
azonenberg_worka guy i was doing consulting with a while ago needs a sample tested under vacuum18:51
azonenberg_workand is buying me a bell jar and mechanical pump18:51
azonenberg_workthe chamber has feedthroguhs rated to 30A18:52
azonenberg_workWhich means that if i can get myself a diffusion or turbopump, setting up a sputtering or filament evaporation system is well within the realm of feasibility18:52
mrdatawhat pressure will the bell jar reach?18:52
azonenberg_workIts rated to high vacuum iirc18:52
mrdata1 torr?18:52
azonenberg_worki dont have full details18:52
azonenberg_workHis tests dont need to go too deep18:53
azonenberg_workPersonally, i'd like to hit 1E-618:53
azonenberg_workwhich would let me do evaporation18:53
azonenberg_worksputterin i could do at around 1E-1 or -218:53
azonenberg_workDC sputtering*18:53
azonenberg_workI wont know for sure until itry pumping it down18:54
azonenberg_workAlso, tonight i am going to try running some polishing experimnents18:54
azonenberg_worksee if i can take a rough chunk of some material (silicon? metal plate?) and get it to an optical polish or better18:55
azonenberg_work1500 grit sandpaper, 6-3-1 um diamond paste18:55
azonenberg_work50-250nm diamond paste18:55
azonenberg_workthen 60nm colloidal silica CMP18:55
mrdataif you had to start from nothing, in the woods, with 18th century equipment, what could you do18:58
azonenberg_workIt'd take a while, i dont have the chemistry background18:58
mrdatayou'd have to know metallurgy18:59
azonenberg_workOne of the first things to do would be to build electric motors (not that hard) for a spin coater and polishing machine18:59
azonenberg_workand a vacuum pump18:59
azonenberg_workwhich would be necessary for most of the remaining work18:59
mrdataok, so we'll say you have copper wire (otherwise you have to refine the copper forom ores)18:59
azonenberg_workthis assumes you have 1700s era metallurgy available (reasonably pure copper wire)18:59
azonenberg_workand basic steam powered machine tools19:00
azonenberg_workif you dont have the second, get it first19:00
mrdatayes. but you can use your knowledge of modern methods and equipment, to make those19:00
azonenberg_workGiven the knowledge, they arent that difficult to make19:01
azonenberg_worka few years to get decently working ones at most19:01
azonenberg_workprobably less given a good team19:01
azonenberg_workThe next step is to start building up stocks of raw materials19:01
mrdatamany metals can be made pure by electroforming19:01
azonenberg_workrefining pure metals etc19:01
azonenberg_workas well as synthesizing solvents and such19:01
azonenberg_workThis is not my area of expertise19:02
mrdatayes. i need catalysts19:02
mrdataplatinum, palladium, rare earths,...19:02
azonenberg_workGiven somewhat pure materials, you can use float-zone crystallization to make them purer19:02
azonenberg_workamong other techniques19:02
mrdatayes that works for silicon19:03
azonenberg_workPhotoresist, i have no clue19:03
azonenberg_workthe active ingredient in the stuff i use is some long complicated diazo compound abbreviated DNQ19:03
azonenberg_workin a novolac-epoxy resin19:03
mrdatastarting from metallurgical grade silicon, (~99% pure), make silicon solar cells19:03
mrdatamust purify the silicon to 99.99919:04
azonenberg_workFloat zone might work for that19:04
azonenberg_workRepeat a couple of times19:04
azonenberg_workthen you can do doping of boron and phosphorus compounds by diffusion19:04
azonenberg_workspin-coat a solution of an alcohol-baseed dopant and heat in air to drive in19:05
azonenberg_workif anyone tries it i'd love to hear the results19:08
azonenberg_workif success, great19:08
azonenberg_workif fail, let us know what you tried and how it failed19:08
azonenberg_workso we wont make the same mistake19:08
bart416You'd need a SEM to analyse the mistake though :(19:11
azonenberg_workDepends on how small it was19:11
azonenberg_workmost of my stuff i can do at least some failure analysis under optical microscopy19:11
azonenberg_workAnd i want to build a sem at some point19:12
azonenberg_workyou have no idea :P19:13
azonenberg_workBut knowing the mat sci department's microscopy lab manager has its perks for the short term lol19:13
azonenberg_worki'm last priority in scheduling since i'm not paying, but i can get my analysis done eventually19:14
mrdatamicroscopy is a critical technology19:14
azonenberg_workmrdata: agreeed19:15
azonenberg_workOptical comes first19:15
azonenberg_workyou need to get basic electronics (including single silicon transistors at macroscale) working before you try doing too much of a shrink19:15
mrdatathe scanning/tunneling microscope was a breakthrough19:16
azonenberg_workmrdata: Do optical first19:16
azonenberg_workQuick inspection of large samples in full color19:16
azonenberg_workSTMs shouldnt be too hard to build19:16
azonenberg_worki actually want to make an STM or AFM some time soon19:16
azonenberg_workthen a SEM later on19:16
mrdataif your fab lab is in your living room, how do you handle dust?19:17
mrdatafinger prints?19:17
azonenberg_workmrdata: hair net, lab coat, and rubber gloves19:18
azonenberg_workpretty much eliminates particulates from me19:18
azonenberg_workthe ambent levels are low enough that i can live with them given frequent cleaning (right before a film deposition etc)19:18
mrdataso, maybe a dust remover?19:19
azonenberg_workI have not had any issues with dust in air19:19
azonenberg_workwhen you try shrinking to micron scale or doing mass production cleanroom capability will be nice19:19
Action: mrdata imagines an eavesdropper watching thru the window, and getting very confused and worried19:19
azonenberg_workfor research scale on tens-of-microns features?19:20
azonenberg_worknot a problem19:20
azonenberg_workmrdata: a friend of mine actually got raided by local cops and some federal folks19:25
azonenberg_workneighbor saw vacuum equipment in his basement and called 911 reporting a bomb19:25
azonenberg_workpeople are idiots... but he still hasnt gotten his stuff back and the court case isnt over yet19:25
azonenberg_worka year later19:25
azonenberg_workso i've been very paranoid in terms of making sure i'm up front with the landlord etc about whats going on19:26
azonenberg_workmsds book in plain view, full fire sprinkler coverage19:26
azonenberg_workproper and documented waste disposal19:26
mrdataresidential zoning might forbid some stuff19:26
Action: azonenberg_work lives in Highway Commercial zone ;)19:27
azonenberg_workpermits light industrial work including "laboratories for commercial and academic research and development"19:27
azonenberg_worki looked that uup a while ago19:27
azonenberg_workand after a year and a half of living here my ex-cop landlord (retired chief of police actually) hasnt turned me in19:28
mrdatairf the authorities think youre operating a clandestine lab, they'll shut you down. doesnt matter what you make19:28
azonenberg_workso my best guess is he doesnt think i'm doing anything illegal19:28
mrdataso it's good to make sure you dont try to hide19:28
azonenberg_workI dont work outside on the sidewalk to avoid freakng out the neighbors, obviously19:29
azonenberg_workBut i also dont make any attempt to hide19:29
Action: azonenberg_work makes mental note to add latest purchase of polishing compound to MSDS binder19:29
azonenberg_workwhy does it have to be so expensive19:38
azonenberg_worki feel lke i could make something equivalent for $200ish19:38
cheaterhow is the project coming along :)19:51
azonenberg_workcheater: hi19:52
azonenberg_workQuite well. I did some runs on the 20um process for characterization last night19:53
azonenberg_workthats 800x magnification19:53
cheatersay, is your toolkit mostly geared for digital, or for analog as well?19:53
azonenberg_worknominal line / space dimension 20um19:54
cheater< ignorant19:54
azonenberg_workand i am actually focusing on MEMS, with digital CMOS as a secondary goal19:54
cheaterlet me just say that looks cool19:54
azonenberg_workhttp://colossus.cs.rpi.edu/pictures/2011/September/9-13-2011%20-%20lab/S7301812.JPG is 400x19:55
azonenberg_workevaporated copper on silicon19:55
azonenberg_workThe roughness you see on the copper is actually the photoresist19:55
azonenberg_workwhich has not yet been stripped19:55
azonenberg_workthe copper itself is very flat19:55
cheaterthese mems? http://en.wikipedia.org/wiki/Microelectromechanical_systems19:56
azonenberg_workA comb drive is my current goal19:56
cheaterwhat does that do?19:56
bart416btw azonenberg have you tried using comsol for simulations?19:56
azonenberg_worki hope to have a working one on the 20um process (i.e. 20um fingers at 20um spacing) by end of the year19:56
azonenberg_workbart416: no, i have not19:56
azonenberg_workcheater: its a linear actuator much like a solenoid19:57
azonenberg_workexcept it uses electrostatic instead of magnetic forces19:57
azonenberg_workyou have two sets of parallel plates19:58
azonenberg_workone fixed and one mounted on a spring19:58
azonenberg_workforming a parallel-plate capacitor19:58
azonenberg_workwhen you apply a charge to the plates they attract19:58
cheaterthat is apparent even in capacitors19:58
azonenberg_workExcept in this case capacitance is not the goal, it's motion19:58
azonenberg_workThe capacitance actually wastes energy - every charge/dischage cycle uses power19:59
azonenberg_workThe static power consumption is effectively zero though19:59
azonenberg_workunlike a solenoid19:59
azonenberg_workiow, much like cmos, you only use power when changing state19:59
mrdatawhat about isentropic switches?20:00
azonenberg_worknot familiar with them20:00
mrdatayou only use power when you have to destroy bits20:00
azonenberg_workall of my "real" experience has been working with a group building mems20:00
azonenberg_workand all of my home work has been focused on getting a working comb drive20:01
cheaterso where could a comb drive be applied?20:16
mrdatasome kind of sensor20:18
cheaterwhat about using it to eg change the color of something20:20
azonenberg_workcheater: i dont see that as being too useful20:23
azonenberg_workyou could use it on a mems micromirror20:23
azonenberg_workas, for example, part of a DLP array20:23
azonenberg_workIf you run it backwards (use low voltage to measure capacitance, rather than high to generate a force)20:24
azonenberg_workyou can use it like an accelerometer20:24
azonenberg_workin fact this is how most mems accelerometers work20:24
berndjazonenberg_work, i wonder if your basement czochralski rig is only the beginning of yet another whole stack of tech21:21
berndjspecifically, how do you make wafers from boules21:22
berndj<mrdata> if you had to start from nothing, in the woods, with 18th century equipment, what could you do  <-- wait, i'll get you a link21:23
berndjhmm, could take a while to find.  there was some guy who was building a telegraph from basically nothing21:26
berndjand while you guys are re-bootstrapping tech, i'd propose that we avoid the vacuum tube cul de sac (until we *really* need them)21:29
berndjhttp://immaculatetelegraphy.tumblr.com/post/235171876  there we go21:33
bart416telegraphs are easy enough to build berndj22:20
berndjuhm, this guy extracts metals from ore22:22
bart416so? :P22:27
bart416You can build a telegraph out of things you find on your desk right now most likely22:27
berndjthen again, i could build half a 6-axis robot from what's n front of me22:33
bart416from what's in front of me I couldn' build that much, from what's next to me though lol23:20
bart416Enough transistors to build a small computer xD23:20
berndjhmm, 4 motors and a geiger tube23:32
berndjnow all i need is an xray tube and it could be a weld inspection robot23:33
azonenbergberndj: also, i dont have a CZ rig yet23:34
azonenbergits on the "would-be-cool-but-not-a-high-priority" list23:34
berndji know, just extrapolating :)23:34
azonenbergAlso, i think tonight or tomorrow morning i am gonna try more double patterning23:34
azonenbergthis time with an even shorter exposure23:35
azonenbergsay 1 min per shot rather than 2.523:35
berndjjust how accurately do you need your cuts to be aligned with the crystal planes?23:35
azonenbergSo far? Not very23:35
azonenbergi can handle a few degrees off23:35
berndjhehe, i mean in hypothetical CZ-in-basement setup23:35
azonenbergYou'd set the seed crystal up as accurately as you can based on a cleavage plane23:35
azonenbergand that sets the orientation for the whole rest of the boule23:36
azonenbergAnd are you talking orientation of the wafer normal?23:36
azonenbergOr the flat23:36
berndji suppose it isn't the end of the world if you have < 0.998 0.996 0.005 > instead of <1 1 0> ?23:36
azonenbergFor precise etches you normally calibrate by doing a test etch23:36
azonenbergAnd correct, it isnt23:36
azonenbergin fact, most real wafers are +/- a degree or so afaik23:37
berndjnot at 5┬Ám anyway!23:37
azonenbergspecifically because that tolerance isnt that crucial23:37
berndjthat's good news then23:37
berndjand how would you saw the boule into wafers?  are you positing a diamon wire saw in your basement too?23:37
azonenbergI'd probably get one of those *before* the CZ rig23:38
azonenbergsince its useful for other stuff23:38
azonenbergcross section imaging for example23:38
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