| Sync | azonenberg: my prof told me to try regular photoresist for pcbs | 10:48 |
|---|---|---|
| Sync | it should work pretty good | 10:48 |
| azonenberg | regular resist? | 10:48 |
| azonenberg | define regular | 10:48 |
| Sync | as in the stuff you buy in the electronics store to coat your pcbs | 10:50 |
| azonenberg | as opposed to cmos grade? | 10:50 |
| azonenberg | it'd be cheaper for sure | 10:51 |
| Sync | yeah, he said for our structure sizes and general conditions it is not neccessary to get professional resist | 10:55 |
| azonenberg | what are yo utrying to do ? | 10:55 |
| azonenberg | i've done 5 micron features with pcb resist :p | 10:56 |
| Sync | nothing special, just had a chat with him after the lecture | 10:57 |
| azonenberg | basically, pcb resist isnt trace metal grade | 10:58 |
| azonenberg | but for anything non-cmos it should be fine | 10:58 |
| Sync | trying to do cmos will require some serious effort | 10:58 |
| Sync | the worst enemies are Ni and Au | 10:58 |
| azonenberg | How about K and Na :P | 10:58 |
| Sync | Ni diffuses through Si at room temp | 11:01 |
| Sync | that caused some headaches here | 11:01 |
| azonenberg | or, heaven forbid, Li | 11:01 |
| azonenberg | Si(Li) EDS detectors cant even be turned on at above cryogenic temps :P | 11:02 |
| Sync | yeah but you don't have those on your tweezers :P | 11:02 |
| azonenberg | oh | 11:02 |
| azonenberg | wait, you were using Ni-plated tweezers to handle chips | 11:02 |
| azonenberg | and that caused problems? o_O | 11:02 |
| Sync | yes | 11:02 |
| Sync | it ruined the wafer | 11:02 |
| azonenberg | Did you do any high-temp processing on it? | 11:03 |
| Sync | we were wondering why our HEMTs were so slow | 11:03 |
| Sync | no | 11:03 |
| Sync | they were just sitting around | 11:03 |
| azonenberg | wow | 11:03 |
| azonenberg | i was going to say, it would make sense if you had heated it | 11:03 |
| azonenberg | but at room temp, wow | 11:03 |
| Sync | just from the edge handling | 11:03 |
| azonenberg | The entire wafer? | 11:03 |
| azonenberg | or just dies near it | 11:03 |
| Sync | it was distributed through the whole wafer | 11:03 |
| azonenberg | Wow | 11:04 |
| azonenberg | over how long | 11:04 |
| Sync | not equally but still | 11:04 |
| azonenberg | diffuison over that much of a distance must take a while at room temp through solids, right? | 11:04 |
| Sync | I suspect a few weeks | 11:04 |
| azonenberg | And how did you trace it to Ni contamination? | 11:05 |
| azonenberg | its a heavy metal, i wouldnt expect it to diffuse that fast | 11:05 |
| Sync | we looked at every process step | 11:05 |
| azonenberg | Na or K i could understand | 11:05 |
| Sync | because it just did not make sense that the devices were so slow | 11:05 |
| Sync | so it HAD to be metal contamination | 11:05 |
| Sync | but we could not see why | 11:05 |
| azonenberg | So more to the point, when you changed tweezers | 11:06 |
| Sync | and then we did one wafer being anal no metal came in contact with | 11:06 |
| azonenberg | did the problem go away? | 11:06 |
| Sync | and it worked | 11:06 |
| Sync | yes | 11:06 |
| azonenberg | wow | 11:06 |
| azonenberg | And you're sure it was Ni | 11:06 |
| azonenberg | rather than, say, K contamination on that particular pair of tweezers? | 11:07 |
| Sync | those were Ni plated stainless tweezers only used to handle wafers | 11:07 |
| Sync | in our flowbench | 11:08 |
| azonenberg | Did you do any testing on those tweezers, i mean | 11:08 |
| azonenberg | to confirm | 11:08 |
| Sync | we put them in the ultrasonic cleaner and tried again | 11:08 |
| Sync | and it still failed | 11:08 |
| azonenberg | Hmm, interesting | 11:08 |
| azonenberg | because i'd believe it was metal contamination | 11:08 |
| Sync | so we are pretty confident that it is ni | 11:08 |
| azonenberg | but i'm skeptical that it's the actual tweezer metal | 11:08 |
| azonenberg | as opposed to a contaminant | 11:08 |
| azonenberg | Is Ni known to diffuse at room temp? | 11:09 |
| azonenberg | it just seems counterintuitive that something so heavy would diffuse from momentary contact at room temperature with no high-temp processing | 11:09 |
| azonenberg | if you had a metal chip on the wafer and put it in a furnace i could understand | 11:09 |
| azonenberg | through a whole wafer no less ,rather than just the dies near where it was handled | 11:10 |
| Sync | it was strange | 11:10 |
| Sync | we did not really investigate after we found the issue | 11:11 |
| Sync | it seems the selfdiffusion rate is around 10^-8m²/s | 11:11 |
| Sync | it was a really strange problem | 11:12 |
| azonenberg | i mean for B and P i'm used to hearing of tens of minutes to hour diffusions at 1200C | 11:12 |
| azonenberg | and thats for a few microns | 11:12 |
| azonenberg | i wouldnt expect horizontal diffusion through several cm of Si to take place at room temp at any appreciable rate | 11:13 |
| azonenberg | as opposed to if you were diffuisng in through the surface from contamination in a bath etc | 11:13 |
| Sync | plz wait, I have to start my process | 11:13 |
| azonenberg | Does your lab have a rule about only CMOS-grade resist on the coaters? | 11:14 |
| azonenberg | the cleanroom here does | 11:14 |
| Sync | I don't think so | 11:15 |
| Sync | I suspect that there was some thermal process after that. | 11:18 |
| azonenberg | after you handled them? | 11:18 |
| Sync | just reading some protocols again | 11:18 |
| azonenberg | And was there an RCA clean first? :P | 11:19 |
| azonenberg | if not, there's your problem :P | 11:19 |
| Sync | we always hf dip, priahna, ozone and hf dip wafers before every process | 11:19 |
| azonenberg | is piranha good at trace metals? | 11:20 |
| azonenberg | i'm used to using RCA-2 for that | 11:20 |
| Sync | we ususally have no trace metal on the surfaces | 11:20 |
| azonenberg | well you did this time | 11:21 |
| azonenberg | which is why i'm asking | 11:21 |
| Sync | we used wafers from the same carrier | 11:22 |
| Sync | and the same prep | 11:23 |
| Sync | and after we changed the tweezers it was fine | 11:23 |
| Sync | aha. | 11:29 |
| Sync | the wafers had some heating done to them in the 400-600°C range but not all of them where we made lifetime measurements | 11:30 |
| azonenberg | and were they cleaned before that? | 11:30 |
| azonenberg | if not, there's your problem | 11:30 |
| Sync | and in those that were kept at room temperature it was less pronounced | 11:30 |
| Sync | yes they have gone through our regular process | 11:30 |
| azonenberg | RT diffusion i would expect little to none, 600C is significant | 11:30 |
| azonenberg | no, i mean during the lifetime measurements | 11:31 |
| azonenberg | were they cleaned before going in the oven? | 11:31 |
| Sync | yes | 11:31 |
| azonenberg | Your clean sucks :P | 11:31 |
| Sync | so how does that explain the bad lifetime on the wafers that were just stored for further processing? | 11:33 |
| Sync | :P | 11:33 |
| Sync | something strange was going on obv. | 11:33 |
| soul-d | so no NERD_N_130F in mail yet :( would expected this revision in stock since it was used as example | 11:37 |
| azonenberg | soul-d: Lol | 11:37 |
| soul-d | no complaint information either | 11:37 |
| soul-d | can't even complain | 11:37 |
| azonenberg | Yeah, the resellers have a habit of taking a long time | 11:37 |
| azonenberg | and if you go to the vendor you have to wait for the 9-month factory lead time plus many years of firmware updates | 11:38 |
| azonenberg | why cant they just ship with full firmware images from the factor??? | 11:38 |
| azonenberg | factory* | 11:39 |
| soul-d | you might want to include an age code :P | 11:39 |
| soul-d | _xxJ would be comon on chips to | 11:39 |
| azonenberg | soul-d: standard JEDEC date code will be included in the packaging information section | 11:40 |
| Action: azonenberg is date code 9033 :P | 11:40 | |
| soul-d | anhow http://imgur.com/jnpEC would expected beter then 30 mA but i should probably focus on measureing the resitance maybe put in a coil of few can's and get rid of paint of it first | 11:42 |
| azonenberg | what is this apparatus? | 11:42 |
| soul-d | target is generating oxigen | 11:42 |
| azonenberg | i see a red bull can and a hose, that can't be good | 11:42 |
| soul-d | outer can is - | 11:42 |
| Sync | wat. pressure just went through the roof in thermal cleaning | 11:42 |
| soul-d | adn the can is the sacrificial one | 11:43 |
| soul-d | should gerate oxigen if im correct :P | 11:43 |
| soul-d | outer can should generate hydrogen and be protected a bit but did read metal can have hydrogen somthign failure and become brittle | 11:44 |
| Sync | hydrogen embrittlement | 11:44 |
| Sync | but that is not going to be a problem there | 11:44 |
| Sync | mostly pronounced when welding | 11:45 |
| soul-d | and i want to oxdize copper :P to cuprous oxide or somthing so don't realy expect much since i doubt reaction happens quick but formula din't mention heat or something | 11:47 |
| soul-d | now i only have to figure out how to increase current to reasonably test it | 11:52 |
| Sync | how about just heating copper? | 11:53 |
| soul-d | no thats the black oxide | 11:53 |
| soul-d | i want the red one cuprous (i) oxide | 11:53 |
| soul-d | one is CuO other is Cu2O | 11:55 |
| Sync | ah yes true | 11:57 |
| soul-d | im doing it to learn an do some chemistry ofcourse i could probable buy most stuff cheaply | 11:58 |
| Sync | bah | 13:22 |
| Sync | goddamn machine | 13:22 |
| --- Thu Nov 22 2012 | 00:00 | |
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