| kristianpaul | CNC? you could start tring some FDM/Electrolitic building block system too ;-) | 00:54 |
|---|---|---|
| azonenberg | lol | 01:50 |
| azonenberg | one thing at a time | 01:50 |
| azonenberg | I want a joystick that lets me move it around and snap pictures on command | 01:50 |
| azonenberg | then the ability to script it for scanning of large areas | 01:51 |
| azonenberg | so i can image an entire chip (or even wafer) without human interaction | 01:51 |
| kanzure | azonenberg: are you practiced in the art of chip decapitation? | 04:59 |
| azonenberg | kanzure: I wrote this article http://siliconpr0n.org/wiki/doku.php?id=tutorial:tutorial_on_epoxy_decapsulation | 05:04 |
| azonenberg | you tell me | 05:04 |
| kanzure | tough call, hmmmm | 05:05 |
| azonenberg | I don't currently have any HNO3 in my lab, I usually let my friend john (the other guy behind siliconpr0n) do the wet lab work | 05:06 |
| azonenberg | He also has a computer-controlled microscope which is able to do automated mass imaging of a large die while i have to take all my pictures by hand | 05:06 |
| azonenberg | i'm catching up, ordered the first batch of parts to CNC my microscope today | 05:06 |
| azonenberg | and i now have a homebrewed fume hood so i'm less concerned about fumes from decapping | 05:06 |
| azonenberg | Why do you ask? | 05:07 |
| hideo | azonenberg: are you walter white? | 05:11 |
| azonenberg | hideo: lol no | 05:11 |
| hideo | :P | 05:12 |
| azonenberg | I do have blue crystals in a cabinet | 05:12 |
| azonenberg | But they're blue raspberry rock candy | 05:12 |
| azonenberg | One of my roommates was watching the show and i freaked him out tossing the packet at him :P | 05:12 |
| azonenberg | you should have seen the look on his face | 05:12 |
| hideo | hahaha | 05:12 |
| hideo | you don't watch bb? | 05:13 |
| azonenberg | Not regularly | 05:13 |
| azonenberg | i've seen a bit here and there | 05:13 |
| hideo | it's really good | 05:13 |
| azonenberg | Most of what I "watch" these days is man pages | 05:13 |
| azonenberg | and journal articles | 05:13 |
| hideo | it's the only tv i watch | 05:13 |
| azonenberg | I probably have another month or so of work to do on general lab tooling | 05:14 |
| azonenberg | then build the spin coater and mask aligner | 05:15 |
| azonenberg | at which point i can start pushing hard | 05:15 |
| azonenberg | see if i can get good patterning in, say, spin-on glass across a full 2" wafer | 05:15 |
| azonenberg | I also need to get a good anisotropic silicon etchant and photoresist developer that are metal-free | 05:15 |
| azonenberg | I've been using NaOH and KOH in the past since MEMS aren't ion sensitive | 05:16 |
| azonenberg | but if i want to do CMOS that'll have to stop | 05:16 |
| azonenberg | TMAH is a bit nasty but i have an interesting idea | 05:16 |
| azonenberg | Since in, i think, both cases it's the OH- that does the dirty work | 05:16 |
| azonenberg | what's a nice nonmetallic organic base that's easy to find? Ammonium hydroxide | 05:16 |
| azonenberg | Somewhat more volatile than TMAH but much easier to get hold of | 05:16 |
| hideo | try it and see | 05:19 |
| azonenberg | For developer, you dont need very aggressive | 05:19 |
| hideo | yeah | 05:19 |
| azonenberg | And for etch, well | 05:19 |
| azonenberg | i dont expect to do through-wafer etches with it | 05:19 |
| azonenberg | for MEMS i can use KOH | 05:20 |
| hideo | tmah is usually diluted as developer | 05:20 |
| azonenberg | Yeah | 05:20 |
| azonenberg | What i mean is, i want to put alignment marks in the silicon | 05:20 |
| azonenberg | to line implants up against | 05:20 |
| azonenberg | That will also function as a test etch for finding orientation if i'm doing KOH etc later on | 05:20 |
| azonenberg | So i only need to go down maybe half a micron, enough to leave a visible edge | 05:20 |
| azonenberg | Thats a more difficult problem i can deal with later | 05:21 |
| azonenberg | but if straight ammonia, perhaps diluted, is usable as developer i'm fine | 05:21 |
| azonenberg | Just have to get something with the same OH- concentration as ~1% TMAH | 05:21 |
| azonenberg | iirc thats whats usually used | 05:21 |
| azonenberg | but for aggressive Si etching you'd use 30% KOH and probably TMAH at a similar concentration | 05:22 |
| hideo | do you have DI water? | 05:22 |
| azonenberg | As of now, just distilled | 05:22 |
| azonenberg | I've focused on lithography and it's pure enough for that | 05:22 |
| azonenberg | i haven't attempted to make transistors | 05:22 |
| azonenberg | it's sat in the plastic jugs for enough months it probably isnt DI grade | 05:22 |
| azonenberg | They're HDPE though so it probably hasnt picked up many metal ions | 05:23 |
| azonenberg | CMOS is a whole other ball game in terms of the necessary purity etc | 05:25 |
| azonenberg | thats why i'm trying to do a comb drive as a first step | 05:25 |
| azonenberg | it demonstrates patterning at the necessary scales but is much more tolerant of ionic contamination | 05:25 |
| azonenberg | And i think i can pull it off in <110> Si with KOH if i angle things right | 05:39 |
| hideo | gah unfortunately i can't say much | 05:40 |
| azonenberg | My plan is to start out by taking a wafer with a single metal layer over oxide, pattern that single metal layer | 05:41 |
| azonenberg | then put overglass over it | 05:42 |
| azonenberg | do flip-chip BGA bonding | 05:42 |
| azonenberg | Just metal, no active components | 05:42 |
| azonenberg | That will let me test metal patterning as well as packaging | 05:42 |
| azonenberg | The next step will be two or three metal layers with CMP in between | 05:42 |
| azonenberg | I'm tentatively thinking copper damascene in spin-on glass | 05:43 |
| hideo | cmp? chem-mechanical polishing? | 05:43 |
| azonenberg | yes | 05:43 |
| azonenberg | if i use thick SOG as the ILD, i might get enough planarity from that | 05:43 |
| azonenberg | Anyway, once i demonstrate a full BEOL process including packaging and flip-chip bonding | 05:45 |
| azonenberg | then i'm going to try doing a MEMS FEOL process for doing the comb drive | 05:45 |
| azonenberg | At the end of that i should be able to make a comb drive in FCBGA | 05:45 |
| azonenberg | four balls, two on each electrode (for stability) | 05:46 |
| azonenberg | 500um wafer thickness on the rim for stability, then back-thinned to ~50um in the active area | 05:46 |
| azonenberg | then through wafer etch with the finger pattern | 05:46 |
| azonenberg | it wont be nearly as nice as if i had DRIE but i dont know of any homemade MEMS ever | 05:46 |
| azonenberg | The next step will be to duplicate Jeri Ellsworth's CMOS FEOL process and shrink to the 12.5¼m node using my litho process | 05:47 |
| azonenberg | and stick my BEOL on top | 05:47 |
| azonenberg | At which point i should be able to make a 2" wafer full of CD4000 chips and hopefully at least a few of them will work | 05:48 |
| azonenberg | complete with overglass around the bond pads and solder bumps | 05:48 |
| azonenberg | That will be the biggest milestone | 05:48 |
| azonenberg | from then on it's just improving yields until i can make something as big as a microprocessor | 05:49 |
| azonenberg | Debating between making an i4004 (from the original released mask art) | 05:49 |
| azonenberg | and trying to make a custom CPU | 05:49 |
| azonenberg | Do you know if anyone's ever made a BGA-packaged i4004? ;) | 05:50 |
| hideo | nope | 05:52 |
| azonenberg | The other possibility, like i said, is a custom CPU | 05:53 |
| azonenberg | Depends in part on where my yields are at that point and what process node i'm at | 05:53 |
| azonenberg | i can get cheap plastic film masks down to 12.5¼m design rules (3.125¼m pixels, 4 pixel min-feature design rules) | 05:54 |
| azonenberg | if i want to go finer i'm probably going to have to either kick out major $$$ for chrome on glass | 05:54 |
| azonenberg | Or ditch contact lithography | 05:54 |
| azonenberg | move to projection and build myself a stepper | 05:54 |
| azonenberg | with 4x reduction or so | 05:54 |
| azonenberg | Right now i'm using projection but there's no stepping/scanning | 05:54 |
| azonenberg | so i'm limited to one objective FOV, which is tiny | 05:55 |
| azonenberg | i'm moving to full-wafer contact in the short term but i want to make a stepper/scanner in the long term | 05:55 |
| azonenberg | It also depends on where i am in my education/career at that point | 05:56 |
| azonenberg | once i get out of school and save up for a few years i'm planning to build myself a house (if you can call it that) with a class 1000 cleanroom and a few other nice lab facilities | 05:56 |
| azonenberg | i could quite plausibly be able to do submicron features reliably, though likely not with great yields | 05:56 |
| azonenberg | RIE isn't even out of the question in the long term | 05:57 |
| azonenberg | if i could get the proper plumbing installed and find some cheap stuff used from an old 500nm fab someone is shutting down etc | 05:57 |
| azonenberg | SF6 only would probably be a good initial setup | 05:58 |
| azonenberg | Since if i could do nice vertical trenches in oxide, i could do copper damascene | 05:59 |
| azonenberg | The first step would be sputtering or evaporation, i NEED in-house metal deposition capability more than really sharp etches | 05:59 |
| azonenberg | i'm pretty sure i can do at least 12¼m features reliably with wet etching | 05:59 |
| Sync | azonenberg: for that feature density you don't really need a cleanroom | 13:05 |
| Sync | we do most stuff on laminar flow benches and yields are good | 13:05 |
| azonenberg | Sync: good to know | 17:45 |
| azonenberg | i want to go smaller thoguh | 17:45 |
| azonenberg | 500nm or even 350 in the long run | 17:45 |
| --- Tue Jul 31 2012 | 00:00 | |
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