| --- Mon Dec 16 2013 | 00:00 | |
| berndj | with the recent paranoia about NSA-infected random number generators, how hard would it be to decap some chips and put them under the microscope to check if their built-in RNGs really do what it says on the tin? | 16:52 |
|---|---|---|
| nats` | the biggest problem in my opinion would be to reconstruct the RNG circuit and see if it's a real one | 16:53 |
| nats` | + other part of the chip could come and manipulate some value like Vgate etc... | 16:54 |
| nats` | I'm not sure it's better than a statistic analysis of the output | 16:54 |
| soul-d | http://people.umass.edu/gbecker/BeckerChes13.pdf | 17:00 |
| soul-d | it explains a few facets your intrested in and also have a conclusion you'r not gonna like | 17:00 |
| azonenberg | soul-d: actually i'm collaborating with the folks behind that paper | 17:31 |
| azonenberg | There's a few things they didn't think of | 17:31 |
| soul-d | :) | 17:35 |
| azonenberg | I'm just gonna stick this in here http://colossus.cs.rpi.edu/pictures/2013/November/11-25-2013%20-%20xc2c32a%20SEM/jpegs/xc2c32a_dash_27_se_4500x_10kv_12mm_annotated.jpg | 17:35 |
| soul-d | mmm what you break ? | 17:36 |
| berndj | i still struggle to read those micrographs | 19:36 |
| Sync_ | the problem is that looking at them with a microscope is not really enough | 20:01 |
| berndj | is there any way to tell n-type from p-type just by looking at the scan? | 20:08 |
| berndj | from what i've seen you can at least see boundaries between (some?) types of doped areas | 20:08 |
| berndj | is that due to the doping or due to different oxide/nitride layer thicknesses? | 20:09 |
| nmz787 | looks like there's height diffs too in addition to brightness | 20:09 |
| nmz787 | brightness could be due to shifts in composition, but height would do it too, so hard to tell | 20:09 |
| nmz787 | azonenberg: I was wondering what you think of achieving 1 micron features relatively close together with a DLP projection system, and maybe a microsope. Currently I can get the focus of the projector down to about 1024 pixels across 1cm, so that's ~25.4 microns per pixel, but I dunno how much diffusion will occur. I have some PCB resist and some old (expired) SU-8 that IDK if would still work | 20:12 |
| azonenberg | berndj: In general you cannot tell doping from a micrograph | 20:13 |
| azonenberg | That image is after a selective stain process to highlight P doping | 20:13 |
| azonenberg | i grew oxide over P-type implants with dash etch | 20:13 |
| azonenberg | nmz787: Not sure | 20:14 |
| azonenberg | I've been away from this project for a while due to lack of time and funding | 20:14 |
| azonenberg | once i have a real job and am out of grad school i plan to get back to it | 20:14 |
| nmz787 | azonenberg: lemme know if you move to Oregon :P | 20:14 |
| nmz787 | azonenberg: intel is building tons of new fabs | 20:14 |
| nmz787 | azonenberg: what about theorhetically, off the top of your head? | 20:15 |
| nmz787 | any ideas? | 20:15 |
| nmz787 | I have been talking with a resist company TOK and they've given me some simulation stuff in response to some of my questions/desires | 20:15 |
| azonenberg | I'd say you definitely want additional optics | 20:15 |
| azonenberg | there was a paper on doing DLP for MEMS | 20:16 |
| nmz787 | yeah i may have it | 20:16 |
| azonenberg | i am more inclined to do 405nm laser direct write | 20:16 |
| nmz787 | well, dunno for mems, but it was a relatively DIY paper | 20:16 |
| nmz787 | yeah but with direct write you then need interferometers for feedback, which makes everything super vibration noise prone | 20:17 |
| nmz787 | you might get around it with a DVD player like optical voice coil focus, but write time would be slow | 20:18 |
| nmz787 | and a camera for inspection | 20:18 |
| azonenberg | You dont necessarily need interferometers | 20:19 |
| azonenberg | I was thinking of doing optical stages with rotary encoders | 20:19 |
| azonenberg | That would get me down to a few microns i think | 20:19 |
| azonenberg | as in, assume the leadscrew is precise and just measure angular position | 20:20 |
| azonenberg | i have some for example that are 250 microns per turn | 20:20 |
| azonenberg | a 256-tick encoder gives me slightly submicron positioning | 20:20 |
| nmz787 | i'm interested in microfluidics, and need to have straight walls and curves reproduced correctly, so leadscrew assumption is hard for me to get over | 20:30 |
| nmz787 | i figure TI has done the hard work for me re: precision, as long as any optics don't distort the image too much | 20:31 |
| Sync_ | nmz787: leadscrews will do your trick nicely | 20:46 |
| Sync_ | c3 precision and everything is pretty easy | 20:46 |
| nmz787 | c3 precision? | 20:50 |
| Sync_ | yes | 20:51 |
| nmz787 | googling | 20:51 |
| Sync_ | it basically tells you the integrated deviation over 300mm | 20:51 |
| Sync_ | in µ | 20:51 |
| Sync_ | so with c3 you get 8µ in 100mm | 20:52 |
| Sync_ | mostly it is less | 20:52 |
| Sync_ | I got some c3 ones in my microstages and I'm hitting +-1µ over 50mm | 20:53 |
| nmz787 | how much would a set cost? | 20:53 |
| nmz787 | is there a c4 grade? | 20:53 |
| nmz787 | :D | 20:54 |
| Sync_ | there is | 20:54 |
| nmz787 | i am working on microstepping now with arduino | 20:54 |
| Sync_ | well that depends on the pitch and diameter | 20:54 |
| Sync_ | but my 1mm lead 10mm diameter ones are about 1k for 130mm long ones | 20:54 |
| Sync_ | the length is not the issue with cost but the nut | 20:55 |
| nmz787 | hmm, well my DLP was $30 on ebay in decent enough shape (no bulb). I can shine a laser in that and get a decent image | 20:56 |
| Sync_ | I have some of those cheap dell DLPs here | 20:57 |
| Sync_ | I messed around with the a bit but in the end microstages are easier and more reliable imho | 20:58 |
| nmz787 | for a large effective surface I'd still need a stage though | 20:58 |
| nmz787 | microstepping and/or moving the image around the DLP area could help with fine alignment of sections | 20:58 |
| Sync_ | stages are also cheap | 21:02 |
| --- Tue Dec 17 2013 | 00:00 | |
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