azonenberg changed the topic of #homecmos to: Homebrew CMOS and MEMS foundry design | Wiki: http://homecmos.drawersteak.com/wiki/Main_Page | Repository: http://code.google.com/p/homecmos/ | Logs: http://en.qi-hardware.com/homecmos-logs/
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<whitequark> It's a metamaterial made by patterning silicone! We can do any amount of these right with very little issues
<whitequark> er
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<SpeedEvil> Shiny disco balls.
<SpeedEvil> Also - lolz.
<SpeedEvil> they usually require sophisticated designs with nonspherical surfaces that can be difficult to polish.
<SpeedEvil> yeah.
<whitequark> I wonder if it would be really easy to pattern that, even DIY
<SpeedEvil> I mean patterning a wafer is entirely trivial.
<whitequark> contamination doesn't matter
<whitequark> the pattern is just fucking circles
<whitequark> that sounds like an awesome idea for a test
<SpeedEvil> An errors mean that you simply lose contrast
<whitequark> yep
<SpeedEvil> 50% error means a 50% contrast lens
<SpeedEvil> Also, the above is clearly infrared only
<SpeedEvil> you'd need to work something else out for visible
<whitequark> "Photo of a high contrast transmitarray lens designed for red light (650nm)"
<SpeedEvil> The lens is made of over 140 million 360nm-tall amorphous silicon nano-posts.
<whitequark> oh, lithography
<SpeedEvil> that would make the posts 100nm or so in diameter
<SpeedEvil> 50-100nm
<SpeedEvil> That seems challenging to do at home.
<whitequark> hm
<SpeedEvil> In principle, linear features might work I think.
<whitequark> well, you could really settle for infrared, a CMOS camera can capture it
<SpeedEvil> not so much.
<whitequark> not so much to what part?
<SpeedEvil> For obvious reasons, the silicon photodetector doesn't work so well at wavelengths silicon is transparent in.
<whitequark> um
<whitequark> i have seen it with my own eyes
<whitequark> tell me it doesn't work XD
<SpeedEvil> You've seen imaging with a conventional camera through a silicon lens?
<whitequark> oh
<SpeedEvil> I'm not saying conventional cameras don't pick up IR
<whitequark> yes, I got your point
<SpeedEvil> An if you can back-thin the wafer to 1um as they did in the paper, you can get it to work. That seems almost as challenging as etching
<whitequark> wait, no, if the camera has a silicon sensor that detects IR, how come silicon would be transparent to IR in that same rnage in the lens?
<whitequark> as for back-thinning the wafer, I was thinking of growing epitaxial silicon on something and then etching it
<SpeedEvil> Silicon is used as IR windows on thermal cameras at 10um - it's got decent ttransmissivity
<SpeedEvil> Also - I wonder if it would be possible to CVD actual glass or some transparent oxide into the required form
<whitequark> glass?
<whitequark> isn't it transparent?
<SpeedEvil> yes.
<whitequark> weren't you just saying that being transparent would be an issue?
<SpeedEvil> It should work fine for this, though in a different manner
<SpeedEvil> If the silicon is transparent at the wavelength in question, then the light goes right through the detecor
<_Sync_> whitequark: protip for epi growth you need a substrate
<_Sync_> SpeedEvil: you can CVD PSG
<whitequark> _Sync_: right. dumb suggestion
<whitequark> what about using sputtering to make a film?
<_Sync_> with Si? I actually cannot say what would happen
<_Sync_> I suppose you'd get a mess
<whitequark> yeah, Si
<whitequark> I'm curious.
<whitequark> I'm going to try it, but I'll need to find a SEM somewhere else.
<_Sync_> a sem is not all that useful, get an AFM
<_Sync_> that has no problems with atom size resolution
<whitequark> wouldn't that only allow to peek at the surface of the film?
<_Sync_> yup but after you got a single layer down you will get epi
<whitequark> hm makes sense
<whitequark> actually that sounds like a very interesting method, i bet there's something in the literature
<_Sync_> well it's not too interesting for everything semi related
<whitequark> hm, from what i could find, people are growing actual high-quality epitaxial films *with* sputtering
<whitequark> 350°C, huh
<_Sync_> sure but not without a si substrate
<_Sync_> 350°C sounds reasonable
<whitequark> right
<whitequark> hm, no one seems to be interested in sputtering silicon on anything except monocrystalline substrates
<_Sync_> that is because it makes no sense
<whitequark> pffff, when did that stop academics
<_Sync_> when they have to apply for grant money
<whitequark> hm, related question. what are the advantages to RF sputtering? no charge buildup?
<whitequark> or rather, apart from lack of charge buildup
<_Sync_> you can sputter nonconductive materials
<whitequark> oh, right.
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<whitequark> wait they quit
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