| azonenberg | Woo | 03:38 |
|---|---|---|
| azonenberg | Just finished a test of Cu patterning | 03:38 |
| azonenberg | Complete success | 03:38 |
| azonenberg | Pics uploading now, still writing up lab notes | 03:39 |
| wolfspraul | success sounds good! | 03:40 |
| wolfspraul | kristianpaul and I added an entry about your work in the news we will push out Monday http://en.qi-hardware.com/wiki/Copyleft_Hardware_News_2011-08-08#Homebrew_CMOS_and_MEMS_foundry | 03:41 |
| azonenberg | Another 20um feature size nyan cat | 03:41 |
| azonenberg | I have a much better photo for you to use | 03:41 |
| azonenberg | still uploading | 03:41 |
| azonenberg | The ones you have were overetched | 03:42 |
| azonenberg | uploading to http://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-08-06/ | 03:43 |
| azonenberg | i'll send exact links when they're done | 03:43 |
| wolfspraul | I confess that I am mirroring your entire images/homecmos folder :-) | 03:43 |
| azonenberg | Lol be my guest | 03:43 |
| wolfspraul | because it's so good, want to be able to browse you quickly with my feh viewer | 03:43 |
| wolfspraul | so I can show people and browse them through your greatness | 03:43 |
| wolfspraul | seriously | 03:43 |
| wolfspraul | it's good work | 03:44 |
| azonenberg | today's stuff has another minute left to upload then you can grab it | 03:44 |
| azonenberg | i'll narrate when its done | 03:44 |
| Action: azonenberg finishes writing lab notes | 03:44 | |
| wolfspraul | yes, and that too | 03:44 |
| wolfspraul | very methodical notes, good pictures. it's a joy. | 03:44 |
| wolfspraul | now we only need to find a way to bring this into use cases... | 03:44 |
| wolfspraul | which should slowly emerge out of it, somewhere | 03:45 |
| azonenberg | Lol | 03:45 |
| azonenberg | I'll have a comb drive soon, if luck is with me | 03:45 |
| azonenberg | most of the big problems are solved | 03:45 |
| azonenberg | -- photos done uploading | 03:45 |
| CIA-67 | homecmos r107 | trunk/lithography-tests/labnotes/azonenberg_labnotes.txt | Today's lab notes - moar nyanotechnology! | 03:48 |
| azonenberg | http://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-08-06/S7301594.JPG and 1595 were my first attempt after developing but before etch | 03:50 |
| azonenberg | mag is 100 and 400x respectively, still 20um pixels | 03:50 |
| azonenberg | 1596 and 1597 were after etching (not long enough) | 03:50 |
| wolfspraul | the problem is I also have the toped screenshot | 03:50 |
| azonenberg | 1598 is after a proper etch | 03:50 |
| wolfspraul | if I change the pic it won't match anymore, would be misleading? | 03:51 |
| azonenberg | 1599 is 40x, 1600 is blurry, 1601 is 400x | 03:51 |
| wolfspraul | or is that screenshot still accurate? | 03:51 |
| azonenberg | I used the same mask | 03:51 |
| azonenberg | this was just another exposure off it | 03:51 |
| azonenberg | using different etch parameters | 03:51 |
| wolfspraul | ah ok | 03:51 |
| azonenberg | same size, too | 03:51 |
| wolfspraul | nice | 03:51 |
| azonenberg | then 1602 is 40x after stripping photoresist | 03:51 |
| wolfspraul | btw, you say picel size 20um, and then you say the cat is 'about 200 um' | 03:51 |
| wolfspraul | but I count many more than 10 rows, almost 20 | 03:52 |
| azonenberg | 1603 is 100x, 1604 is 400x | 03:52 |
| azonenberg | And let me double check my measurements | 03:52 |
| azonenberg | h/o | 03:52 |
| wolfspraul | you say the cat is 600 um long, 200 um high | 03:52 |
| wolfspraul | but I think the height is more like 300 um | 03:52 |
| azonenberg | Yeah, i think you're right | 03:52 |
| azonenberg | that was probably a typo on my part | 03:52 |
| wolfspraul | well. in all my stupidity, all I can do is to count the rows, and multiply by 20 :-) | 03:53 |
| azonenberg | i count 18 rows so thats 18*20 = 360um | 03:53 |
| wolfspraul | but I guess at least that I did right... | 03:53 |
| azonenberg | so not usre how i got 200 | 03:53 |
| wolfspraul | yep | 03:53 |
| wolfspraul | :-) | 03:53 |
| azonenberg | In any case i'd appreciate you replacing the overetched pics with ones from this die | 03:53 |
| azonenberg | you can keep the screenshot | 03:53 |
| wolfspraul | will do | 03:53 |
| wolfspraul | I have about 500-800 readers | 03:53 |
| azonenberg | Nice :) | 03:54 |
| wolfspraul | and it's buried somewhere in a lot of stuff, but some people will see it I think | 03:54 |
| azonenberg | Cant hurt to get the word out | 03:54 |
| wolfspraul | maybe I bump it to the top | 03:54 |
| R0b0t1 | OMFG NYAN! | 03:55 |
| azonenberg | R0b0t1: Nyanotechnology | 03:56 |
| azonenberg | http://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-08-06/S7301603.JPG is a 100x view of the finished chip | 03:56 |
| azonenberg | each of the pixels are 20 microns (0.02 mm) across | 03:56 |
| wolfspraul | azonenberg: so which pictures would you propose to use? I think two is fine, one zoom out (entire cat), one zoom to just the head | 03:56 |
| wolfspraul | which ones are most representative of your work? | 03:56 |
| azonenberg | I'd say 1603 and 1604 | 03:57 |
| azonenberg | 100x and 400x mag respectively | 03:57 |
| R0b0t1 | I'm glad to see it looked like it finally worked | 03:57 |
| azonenberg | This is my best work to date re metal layer patterning | 03:57 |
| azonenberg | R0b0t1: Yes, it worked beautifully | 03:57 |
| azonenberg | Conveniently Cu is also HF resistant | 03:57 |
| azonenberg | So i can use it as a hardmask for patterning SiO2 or Ta2O5 | 03:57 |
| wolfspraul | the cat is copper on silicon? | 03:57 |
| azonenberg | Yes | 03:58 |
| azonenberg | Blue is Si, orange is Cu | 03:58 |
| azonenberg | evaporated around 200nm Cu on the whole die and then etched down to make the lines | 03:58 |
| wolfspraul | azonenberg: updated http://en.qi-hardware.com/wiki/Copyleft_Hardware_News_2011-08-08#Homebrew_CMOS_and_MEMS_foundry | 04:29 |
| azonenberg | Looks great, thx | 04:30 |
| wolfspraul | thank you, inspiring work, keep it up | 04:30 |
| wolfspraul | is 4004 CPU still on your horizon? or something else now? | 04:30 |
| azonenberg | Its one of the several relatively large scale (1E3 transistor range) devices i'd like to build in the long term | 04:31 |
| azonenberg | Now that metal etching is solved and Si etching is coming along nicely, i think i am very close to a comb drive | 04:31 |
| azonenberg | which is the immediate goal | 04:31 |
| wolfspraul | I'm just trying to understand your mental roadmap, and I fully understand it may change as you move forward and discover more, successes and failures etc. | 04:31 |
| wolfspraul | what is a comb drive? | 04:32 |
| wolfspraul | I am seriously interesting in finding a way to embed some of your stuff on hacker boards or even products I could build | 04:32 |
| wolfspraul | s/interesting/interested/ | 04:32 |
| wolfspraul | not now of course, I understand there's more work to be done first | 04:32 |
| azonenberg | A comb drive is a capacitive linear actuator | 04:33 |
| azonenberg | Let me upload a GDS and i'll walk you through it h/o | 04:33 |
| wolfspraul | I think that would be so cool if we could squeeze out some actual use case out of what you build, from the perspective of a software developer | 04:33 |
| wolfspraul | no matter how small the 'programmability' may be at the beginning | 04:33 |
| wolfspraul | just explaining my perspective | 04:33 |
| azonenberg | Yeah | 04:33 |
| azonenberg | http://colossus.cs.rpi.edu/~azonenberg/downloads/combdrive-2.gds | 04:35 |
| azonenberg | look at the cell TestDie1 | 04:35 |
| azonenberg | In the background we have the backside etch layer | 04:36 |
| wolfspraul | he, I need to install toped first, in fact build from source | 04:36 |
| wolfspraul | let me try... | 04:36 |
| azonenberg | kk, let me know when you have it open | 04:36 |
| wolfspraul | open | 04:50 |
| azonenberg | Ok | 04:52 |
| azonenberg | So the background layer is the backside etch | 04:52 |
| wolfspraul | those 2 big blocks at the top and bottom? | 04:52 |
| azonenberg | No, zoom out further | 04:52 |
| azonenberg | its a ring around the whole thing | 04:52 |
| wolfspraul | yes | 04:53 |
| wolfspraul | I'm zoomed out I think | 04:53 |
| azonenberg | The idea here is to thin out the central part of the die by etching from the back towards the front | 04:53 |
| wolfspraul | I see the text on top and bottom | 04:53 |
| azonenberg | No, its beyond that | 04:53 |
| wolfspraul | "comb drive xx.1" and "2011.x.2." | 04:53 |
| azonenberg | Yeah | 04:53 |
| azonenberg | Further | 04:53 |
| wolfspraul | further out? | 04:53 |
| azonenberg | Yes | 04:53 |
| azonenberg | like by 4x | 04:53 |
| wolfspraul | ok there are 2 squares around it | 04:54 |
| azonenberg | The outer ring is where we keep the wafer at full thickness | 04:54 |
| azonenberg | Everything inside there is thinned down to around 20-30 microns | 04:54 |
| azonenberg | this is done with KOH from the back toward the front | 04:54 |
| azonenberg | The idea is to leave a nice stiff carrier around the edges so we can pick the die up without cracking it | 04:55 |
| wolfspraul | when you say 'ring' you mean the space between the 2 outer squares, right? | 04:55 |
| azonenberg | The outr square | 04:55 |
| wolfspraul | sure I was just confused because when I see 'ring' I think 'round' | 04:55 |
| azonenberg | Its a square ring | 04:55 |
| azonenberg | turn on shading for all of the alyers | 04:55 |
| azonenberg | layers* | 04:55 |
| wolfspraul | yes | 04:55 |
| wolfspraul | I got it | 04:55 |
| azonenberg | Anyway so thats the backside etch | 04:55 |
| azonenberg | Once we have the wafer thinned out, we coat the wafer with hardmask and etch the red mask | 04:56 |
| azonenberg | sorry i forgot gds doesnt have colors lol | 04:56 |
| azonenberg | its the layer that doesnt have text on it | 04:56 |
| azonenberg | 1 i think | 04:56 |
| wolfspraul | yes, no colors right now | 04:56 |
| wolfspraul | in my view | 04:57 |
| azonenberg | This is the active area mask | 04:57 |
| wolfspraul | thinking ahead, how do we cut this out of the wafer and make any i/o pins (power, gnd, data) accessible to the circuit around the chip? | 04:57 |
| azonenberg | The entire background should be protected (I just didnt draw it filled since the mask isnt finished) | 04:57 |
| wolfspraul | in other words - how do we package or seal the chip? | 04:57 |
| azonenberg | Etch this down until we've penetrated the entire die (fingers hang free) | 04:57 |
| wolfspraul | the active area is in the middle I guess | 04:57 |
| azonenberg | then deposit metal and etch the mask with text on it | 04:57 |
| azonenberg | So at this point we have two sets of fingers | 04:58 |
| azonenberg | one mounted on a spring and one hanging free | 04:58 |
| azonenberg | *one mounted on a spring and one attached to the body | 04:58 |
| azonenberg | sorry | 04:58 |
| azonenberg | They're both covered in metal but are isolated from each other electrically | 04:58 |
| wolfspraul | you are talking about packaging now? | 04:58 |
| azonenberg | No | 04:59 |
| azonenberg | still how it works | 04:59 |
| azonenberg | When we apply a voltage across the top and bottom areas, the plates develop a charge and attract | 04:59 |
| wolfspraul | ah ok | 04:59 |
| azonenberg | so the springy fingers move toward the stationary ones | 04:59 |
| wolfspraul | wait, I zoom in :-) | 04:59 |
| azonenberg | then when we remove the voltage they spring back | 04:59 |
| wolfspraul | ok | 04:59 |
| azonenberg | The design here is still early, it needs a lot of tweaking | 04:59 |
| azonenberg | Anyway so this is meant to be used (in the end) as part of a system with moving parts of some sort | 05:00 |
| azonenberg | its basically a linear motor | 05:00 |
| azonenberg | Re packaging, for ICs (rather than MEMS) since they have no moving parts, its relatively easy | 05:00 |
| wolfspraul | it's this I guess... http://en.wikipedia.org/wiki/Comb_drive | 05:00 |
| azonenberg | Yes | 05:00 |
| azonenberg | You'd make the die a mm or two across and scribe it out of the wafer (I separate my dies from the wafer before processing since i only make one die at a time) | 05:01 |
| azonenberg | The top metal layer would be extra thick | 05:01 |
| azonenberg | and then you could wire bond or similar to it (detials of how to attach wires are TBD) | 05:01 |
| azonenberg | but you'd have 50-100 micron wide contact pads around the rim of the chip | 05:01 |
| azonenberg | then you seal it on with a blob of epoxy | 05:01 |
| wolfspraul | is the packaging still part of your lab setup/goal, or would you use a service for that? | 05:02 |
| wolfspraul | wirebond dies typically come in small chocolate-sized vacuum sealed packlets | 05:02 |
| azonenberg | The immediate goal is fab, i'll be testing them with microprobes | 05:02 |
| azonenberg | if and when i build something suitable for actual use in a project i'd think about it then | 05:03 |
| azonenberg | I might be buying/building a wirebonder eventually | 05:03 |
| wolfspraul | then it goes to a wirebond machine to run the wires (aluminum, gold, etc) and put the epoxy on as a last step | 05:03 |
| azonenberg | Yep | 05:03 |
| wolfspraul | all of which is done after smt/reflow because it cannot take heat | 05:03 |
| azonenberg | Interesting, i didnt know that part | 05:03 |
| wolfspraul | of course you know that, I'm just explaining where my current knowledge stops | 05:03 |
| azonenberg | the epoxy cant handle reflow? | 05:04 |
| wolfspraul | I can double-check, haven't done wirebonding for a year or so | 05:04 |
| azonenberg | Because the exact same process (excpet the epoxy is in a chip-shaped mold and has a leadframe around it instead of a PCB) is used for making normal ICs | 05:04 |
| wolfspraul | there are wire-bond modules which in turn go through reflow | 05:04 |
| azonenberg | they wirebond from the die to the leadframe then fill the whole thing with epoxy | 05:04 |
| wolfspraul | maybe some can and some cannot | 05:04 |
| azonenberg | chip on board simply removes some of the middleman | 05:04 |
| wolfspraul | but also adds new ones | 05:05 |
| azonenberg | not really | 05:05 |
| azonenberg | Instead of a separate soldered leadframe you bond from the die straight to the copper traces | 05:05 |
| wolfspraul | in the industry, many smt shops do not have a wirebond machine | 05:05 |
| azonenberg | then epoxy fill over it | 05:05 |
| wolfspraul | for some strange reason | 05:05 |
| azonenberg | I want one :P | 05:05 |
| azonenberg | i've used them in the cleanroom | 05:05 |
| wolfspraul | so if you have a product with wirebond, the logistics and testing has more steps | 05:05 |
| wolfspraul | because stuff is sent around | 05:05 |
| wolfspraul | oh it's no rocket science for sure, I'm just saying it's a separate/different workstep and as such adds complexity to the manufacturing process | 05:06 |
| wolfspraul | which if you have stronger packages, someone else has done this before | 05:06 |
| wolfspraul | the stronger packages come at a price too of course | 05:06 |
| wolfspraul | most wirebond places are small offices, like a dentist | 05:06 |
| azonenberg | interesting | 05:06 |
| azonenberg | Like i said i havent done much COB (except for taking them apart) | 05:07 |
| wolfspraul | I've heard that some smt fabs now add this machine (and workstep) to their arsenal, but I think for the most part it's still separate | 05:07 |
| azonenberg | i've only studied wirebonding as it applies to fabrication of regular ICs | 05:07 |
| wolfspraul | wirebond is definitely disruptive to the manufacturing and testing process | 05:07 |
| azonenberg | or for bonding a prototype die for packaging | 05:07 |
| wolfspraul | so that additional disruption (cost) needs to be made back, which is why you find wirebond typically only in high-volume applications (say 100K units or more) | 05:08 |
| azonenberg | Yeah | 05:08 |
| wolfspraul | oh sure, but that's a completely different use case | 05:08 |
| azonenberg | But as i said its the one i'm familiar with lol | 05:08 |
| azonenberg | Given a wafer, go test it | 05:08 |
| wolfspraul | anyway I am just thinking practical how we go from your wafer to being able to integrate this into a bigger circuit | 05:08 |
| wolfspraul | normally I think the packaging services are also small service providers | 05:08 |
| azonenberg | Depends a lot on how much ends up being doable | 05:09 |
| wolfspraul | you send them a wafer, tell them which package you want, and they send you the packages back | 05:09 |
| azonenberg | In the short term i am not expecting to make anything more complex than 4000 series | 05:09 |
| azonenberg | one die at a time | 05:09 |
| johndmcmaster | on that note, does anyone have a good reference on ohmic contacts | 05:09 |
| johndmcmaster | composition materials and such | 05:09 |
| azonenberg | johndmcmaster: That was on my list of things to research as well | 05:10 |
| azonenberg | i've heard something about platinum silicide being common | 05:10 |
| azonenberg | But for the comb drive i'll be doing evaporated or sputtered metal over thermal oxide | 05:10 |
| azonenberg | iow the Si will be just a substrate and not passing any current at all | 05:10 |
| wolfspraul | so wait, you lost me | 05:10 |
| wolfspraul | we will find some way to package it, let's move that aside now | 05:11 |
| wolfspraul | but how about programmability | 05:11 |
| wolfspraul | what feature can come out of a 'comb drive'? | 05:11 |
| azonenberg | i was pushing that off until i got to CMOS | 05:11 |
| azonenberg | wolfspraul: On and off | 05:11 |
| azonenberg | Its meant to be used as part of a MEMS system | 05:11 |
| azonenberg | moving around micromirrors etc | 05:11 |
| azonenberg | By itself it's useless | 05:11 |
| wolfspraul | ok | 05:11 |
| azonenberg | An x/y micromirror system would be next on the list of more complex devices to build | 05:12 |
| wolfspraul | imaging sensor? | 05:12 |
| azonenberg | no, it'd be a steerable mirror | 05:12 |
| wolfspraul | projector? | 05:12 |
| azonenberg | A chunk of polished Si that can be tilted in various directions | 05:12 |
| azonenberg | Basically a single DLP pixel | 05:12 |
| azonenberg | Which could also be used as the main element in a laser projector | 05:12 |
| wolfspraul | yes :-) | 05:12 |
| azonenberg | It'd probably be sputtered in aluminum or something to make it nice and reflective (like telescope mirrors) | 05:13 |
| azonenberg | Thats next on my todo list once i get a single comb drive built | 05:13 |
| wolfspraul | cool | 05:13 |
| azonenberg | Something of that magnitude would actually be useful | 05:13 |
| wolfspraul | well then, good luck! | 05:13 |
| azonenberg | and probalby not that difficult | 05:13 |
| azonenberg | CMOS is a lot harder due to the sensitivity to trace contaminants | 05:13 |
| azonenberg | The micromirror would basically be two comb drives connected to a block of Si | 05:13 |
| azonenberg | the only hard part would be figuring out how to make it tilt | 05:14 |
| wolfspraul | yes, anything usable first | 05:14 |
| wolfspraul | that'd be great | 05:14 |
| wolfspraul | I will seriously try to make this part of a hacker board or product, in whatever stretch imagination that needs | 05:15 |
| wolfspraul | :-) | 05:15 |
| azonenberg | Any kind of laser projector could use something like this | 05:15 |
| wolfspraul | we take the fabrication of your dies to China! even if made one by one :-) | 05:15 |
| azonenberg | Lol :P | 05:15 |
| wolfspraul | (just kidding) | 05:15 |
| azonenberg | Maybe to improve yields have two independent 1-axis tilt systems | 05:15 |
| azonenberg | that would mean i don tneed to get two working drives on the same die | 05:15 |
| azonenberg | make a working x axis, then a working y axis | 05:16 |
| azonenberg | and mount them 90 deg apart | 05:16 |
| wolfspraul | how is this related to a galvanometer? | 05:16 |
| azonenberg | The intended use case would be very similar | 05:16 |
| wolfspraul | nice | 05:16 |
| azonenberg | A DLP projector is basically a grid of tiny mirror galvos | 05:16 |
| wolfspraul | there's a guy marcan in the #qi-hardware channel now working on his OpenLase project | 05:16 |
| azonenberg | that PWM the reflected signal between "on" (poitned at the screen" and "off" (pointed off to the side) | 05:17 |
| wolfspraul | he takes a normal 2 USD laser pointer, plus galvos and some software | 05:17 |
| azonenberg | And yeah, i saw | 05:17 |
| azonenberg | You could quite possible use a MEMS galvo to do steering of the beam | 05:17 |
| wolfspraul | very cool | 05:17 |
| azonenberg | thats something i'd say is realistic in the 1-2 year time frame | 05:17 |
| azonenberg | based on how fast things are going now | 05:17 |
| wolfspraul | excellent | 05:17 |
| azonenberg | Of course, production would be very limited lol | 05:17 |
| wolfspraul | in that time frame I can work on getting my manufacturing costs further down and efficiency further up | 05:18 |
| wolfspraul | nah don't worry. I will take this to China, then we optimize :-) | 05:18 |
| azonenberg | Lol good luck finding budget for ASIC fab | 05:18 |
| wolfspraul | if Chinese are good at anything, it's process innovation | 05:18 |
| azonenberg | i know guys doing that and it isnt cheap | 05:18 |
| azonenberg | But its an open project so if you do figure out a way to do something cool with my designs, more power to you | 05:18 |
| wolfspraul | why not make them in your very own process? | 05:18 |
| wolfspraul | home-fab | 05:18 |
| azonenberg | I could, it just couldnt be done en masse | 05:19 |
| wolfspraul | ok one by one | 05:19 |
| azonenberg | Right now the biggest issue preventing more rapid production is my exposure system | 05:19 |
| wolfspraul | I would start with 1, then optimize | 05:19 |
| azonenberg | all of the chemical processing and deposition is parallel up to wafer level | 05:19 |
| azonenberg | But i cant expose more than one die (or even part of a die depending on magnification) at a time | 05:19 |
| wolfspraul | understood. nothing better than a few nice challenges, right? | 05:20 |
| azonenberg | i need to work out a laser direct-write system or similar that will let me make a contact mask for a bunch of dies and expose them all at once | 05:20 |
| azonenberg | Its on the longer term todo list | 05:20 |
| wolfspraul | yes | 05:20 |
| wolfspraul | the mems mirror may come in handy? | 05:20 |
| wolfspraul | :-) | 05:20 |
| azonenberg | Lol, maybe | 05:20 |
| wolfspraul | just kidding, I think I understand it | 05:20 |
| azonenberg | i'm serious though | 05:20 |
| wolfspraul | we will find ways to bring this out into real use cases though | 05:20 |
| wolfspraul | early | 05:20 |
| wolfspraul | no matter how limited | 05:21 |
| azonenberg | Would be cool to show people my instruments and say that i am using a homemade chip into the tool | 05:21 |
| azonenberg | And sounds like a plan :) | 05:21 |
| azonenberg | My next goal in the short term is to get 1/4 of a <110> 2-inch wafer prepped, spin coated in a very thin Ta2O5 layer (probably on the order of 50nm) | 05:21 |
| azonenberg | and coated with evaporated Cu | 05:22 |
| azonenberg | On both sides | 05:22 |
| azonenberg | Actually i might even do half a wafer | 05:22 |
| azonenberg | if the tantalum cooperates | 05:23 |
| azonenberg | My proposed process would allow me to do all of the depositions at once and then etch top and bottom separately | 05:23 |
| azonenberg | The one restriction is that once i open a hole in the hardmask i cant close it | 05:23 |
| azonenberg | in other words i'd need to do the bottom etch first and thin down to maybe 30 microns | 05:23 |
| azonenberg | then open up the top (leaving bottom exposed) and etch both down and up | 05:23 |
| azonenberg | the end result would be the fingers on top, parallel with the top surface, and about 15um thick | 05:24 |
| azonenberg | At that point i'd strip the Ta2O5 layer, grow thermal oxide over the whole die (which i need to get a furnace for) | 05:24 |
| azonenberg | evaporate/sputter the whole die in metal and then do one last etch of metal 1 | 05:24 |
| azonenberg | at which point i'd have a completed, ready-to-test prototype | 05:25 |
| wolfspraul | he | 05:25 |
| wolfspraul | I will follow... | 05:26 |
| bart416 | azonenberg, what to do with a shitty old computer | 11:28 |
| R0b0t1 | If you don't already know of a use for it I've found it is best thrown away. | 11:42 |
| bart416 | Yeah but that costs money! | 11:45 |
| bart416 | :| | 11:45 |
| bart416 | (Not a joke) | 11:45 |
| berndj | azonenberg, is it much harder to evaporate Cu than Al? thinking of melting point vs vapour pressure here | 17:17 |
| azonenberg | berndj: Cu and Al can both be evaporated in the unit i've been using | 18:38 |
| azonenberg | I did Cu because it's more resistant to HF than Al | 18:38 |
| azonenberg | In terms of a homebrew setup that's still a ways out | 18:40 |
| bart416 | azonenberg, http://news.vanderbilt.edu/2011/08/nanodiamond/ | 20:38 |
| azonenberg | interesting - CVD diamond for gates? | 20:42 |
| azonenberg | And lol, they require vacuum-sealed packaging to operate? | 20:42 |
| azonenberg | those would be fun to reverse engineer | 20:42 |
| azonenberg | you couldnt probe them without a vacuum chamber | 20:43 |
| azonenberg | which probably would mean a SEM too | 20:43 |
| bart416 | You'd be using a SEM to reverse engineer them anyway :P | 20:44 |
| azonenberg | Not for larger process size devices | 20:44 |
| azonenberg | you can do 350nm with an optical microscope if you're patient | 20:44 |
| azonenberg | 250 and below pretty much needs a SEM though | 20:45 |
| bart416 | Eventhough we never get to do it, us is always told to go for the electron microscope when debugging or reverse engineering electronic devices | 20:49 |
| bart416 | For the simple reason that you can study the device in operation | 20:49 |
| azonenberg | Yeah | 20:49 |
| azonenberg | You can do that with an optical scope too though | 20:50 |
| azonenberg | Just not for really small stuff | 20:50 |
| azonenberg | i have probes and micropositioners already | 20:50 |
| bart416 | Can you "see" electricity with an optical scope? :P | 20:50 |
| azonenberg | and plan to try studying a 4000 series chip live in the near future | 20:50 |
| bart416 | Didn't think so | 20:50 |
| azonenberg | No | 20:50 |
| azonenberg | But i can drop a needle down on top metal and plug that into a logic analyzer | 20:50 |
| azonenberg | And for somethign simple like a 4017 that should give good results | 20:52 |
| azonenberg | 0.190] breadboard kernel: sys_alloc_init: node = a00006e8, node->this_size.size = 153 | 21:01 |
| azonenberg | [ 0.197] breadboard kernel: sys_alloc_init: node->next_free = 00000000 | 21:01 |
| azonenberg | [ 0.204] breadboard kernel: sys_alloc_init: buf->first_free = 00000000 | 21:01 |
| azonenberg | [ 0.210] breadboard kernel: sys_alloc_init: node = a00006e8, node->this_size.size = 29959 | 21:01 |
| azonenberg | [ 0.218] breadboard kernel: sys_alloc_init: node->next_free = 00000000 | 21:01 |
| azonenberg | [ 0.224] breadboard kernel: sys_alloc_init: buf->first_free = a00006e8 | 21:01 |
| azonenberg | whoops wrong tab | 21:01 |
| azonenberg | Though if you guys want to help me debug a sys_malloc() segfault on an embedded MIPS feel free :P | 21:01 |
| R0b0t1 | Psh, allocate on the stack. | 21:05 |
| azonenberg | R0b0t1: I think the segfault is actualyl stack corruption that overflowed onto the heap | 21:06 |
| azonenberg | i only have 32KB of ram so its not hard | 21:06 |
| R0b0t1 | Yeah, seems like it could easily be the problem | 21:06 |
| azonenberg | But its tricky and nondeterministic | 21:06 |
| azonenberg | doesnt happen (or at least not in the same spot) if i disable context switching | 21:06 |
| R0b0t1 | You have 32kb of RAM, and you have context switching...? | 21:08 |
| azonenberg | The PIC32 series has up to 128KB but the chip on my dev board atm is 32 | 21:09 |
| azonenberg | and yes, i have multithreading | 21:09 |
| azonenberg | The kernel will eventually be ported to a MIPS softcore on an FPGA with a ton of DRAM | 21:09 |
| azonenberg | but i want to keep it light enough that i can use it on pic32 still if necessary | 21:09 |
| azonenberg | a thread environment block is only a couple hundred bytes, maybe less | 21:09 |
| azonenberg | 32x 32-bit registers = 128 bytes plus a little metadata | 21:09 |
| R0b0t1 | Oh I keep forgetting programs aren't in RAM | 21:09 |
| azonenberg | Yeah | 21:10 |
| azonenberg | 512KB of memory mapped flash | 21:10 |
| azonenberg | code is all execute-in-place | 21:10 |
| azonenberg | Right now the kernel image, libc, and a bunch of usermod test applications are around 80KB | 21:15 |
| azonenberg | and i'm using under 10KB of ram | 21:16 |
| azonenberg | That will go down as i optimize and trim stuff out of the core image, there's a lot of test code | 21:16 |
| R0b0t1 | nice | 21:16 |
| azonenberg | Well, this is going to be fun - tonight i'm going to try some more silicon etching | 21:46 |
| azonenberg | using my new slow Cu etch to pattern the Cu, then HF through that onto the Ta2O5 and KOH | 21:46 |
| azonenberg | http://www.youtube.com/watch?v=E0yaGF10Kp8 | 23:19 |
| azonenberg | this is a SU-8 polymer comb drive, 300 microns high, 30 micron wide fingers | 23:19 |
| azonenberg | sputtered in gold | 23:19 |
| azonenberg | Something like this or smaller should be very doable | 23:20 |
| azonenberg | this is 30um and my process should be good to 20 at least | 23:20 |
| --- Mon Aug 8 2011 | 00:00 | |
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