7 ms·

Awesome. For those considering exploring some of these steps in their own garage -- the chemistry is dangerous, perhaps HF in particular, as it doesn't hurt, it

by ISL 9y ago

Awesome. For those considering exploring some of these steps in their own garage -- the chemistry is dangerous, perhaps HF in particular, as it doesn't hurt, it just kills you a few hours later. Can you do this in a garage? Absolutely, but learn everything you need to know from an ensemble of safety-minded mentors before you strike out on your own. It's not just about safety for you, proper disposal of these chemicals is essential for the many generations to come. Sometimes it is inexpensive, sometimes it is costly. You need to know how before you start, or it costs a lot more. (Also, you can get someone else to pay for the hardware, the infrastructure, the material, the resists, the reagents, the safety training, and the waste disposal if you work/volunteer at a university's photolithography facility. They'll probably pay you, too.)

88e282102ae2e5b 9y ago
I understand why it's necessary, but I was shocked that he uses piranha in his home garage. I cannot echo the above sentiment enough.
- deleted 9y ago
  [deleted]
Itsdijital 9y ago
Good 'ole HF http://blogs.sciencemag.org/pipeline/archives/2004/03/03/things_i_wont_touch_1 http://blogs.sciencemag.org/pipeline/archives/2004/03/03/thi...
- donpdonp 9y ago
  TL;DR "hydrofluoric acid is a water solution of hydrogen fluoride, HF. That’s a gas, and it’s a lot worse. ... As soon as it hits anything moist – like your lungs – it dissolves in the water and turns into hydrofluoric acid again."
  - lifeisstillgood 9y ago
    or "The straight liquid must really be a treat, but I’ve never seen it in that form, and would only wish to through binoculars."
    - AstralStorm 9y ago
      The fact that it is liquid at relatively balmy temperatures makes it a bit easier to handle than most gases, but then you better have great urethane seals, gloves and clothing everywhere. (Silicones are permeable, PTFE is damaged over time, nitrile and vinyl gloves also leak.)
      - jakeogh 9y ago
        8mil nitrile x2 with no extended(!) contact option. Like silane: http://amo-csd.lbl.gov/downloads/Chemical%20Resistance%20of%20Gloves.pdf http://amo-csd.lbl.gov/downloads/Chemical%20Resistance%20of%...
- msla 9y ago
  Oh, yeah. I knew someone would get around to linking to Derek Lowe and his inimitable "Things I Won't Work With" series. His best-known entry in that series, about chlorine triflouride, also has mention of HF and semiconductors: http://blogs.sciencemag.org/pipeline/archives/2008/02/26/sand_wont_save_you_this_time http://blogs.sciencemag.org/pipeline/archives/2008/02/26/san... > The compound also a stronger oxidizing agent than oxygen itself, which also puts it into rare territory. That means that it can potentially go on to “burn” things that you would normally consider already burnt to hell and gone, and a practical consequence of that is that it’ll start roaring reactions with things like bricks and asbestos tile. It’s been used in the semiconductor industry to clean oxides off of surfaces, at which activity it no doubt excels. > There’s a report from the early 1950s (in this PDF) of a one-ton spill of the stuff. It burned its way through a foot of concrete floor and chewed up another meter of sand and gravel beneath, completing a day that I’m sure no one involved ever forgot. That process, I should add, would necessarily have been accompanied by copious amounts of horribly toxic and corrosive by-products: it’s bad enough when your reagent ignites wet sand, but the clouds of hot hydrofluoric acid are your special door prize if you’re foolhardy enough to hang around and watch the fireworks Here's a video of some French people introducing the substance to things like a rubber glove and leather: http://blogs.sciencemag.org/pipeline/archives/2013/04/05/chlorine_trifluoride_some_empirical_findings http://blogs.sciencemag.org/pipeline/archives/2013/04/05/chl... TL;DW: FIRE!
jjeaff 9y ago
Of course, caution is always warranted when dealing with HF. However, I don't see any reason why it can't be safely used at home. In fact HF is found in lots of commonly used household cleaning products like rust and stain removers. Plenty of people are using Goof Off Rust remover and are not dropping dead later in the day.
- deleted 9y ago
  [deleted]
- basicplus2 9y ago
  Oh man.. you need to talk to those who have worked with the stuff.. The amount in household products is essentially zero and one drop of the pure stuff and you are gone.. this stuff is nightmare material, i know, i have worked with and around it. 70% pure accident.. PFF http://www.ehs.ucsb.edu/files/docs/ls/HF_fatality.pdf http://www.ehs.ucsb.edu/files/docs/ls/HF_fatality.pdf HTML http://www.geo.utexas.edu/geosafety/hf-accident.html http://www.geo.utexas.edu/geosafety/hf-accident.html 10% strength MSDS HTML http://www.kendon.com.au/Catalogue/MSDS/Industrial/10%25Hydrofluoricacid.htm http://www.kendon.com.au/Catalogue/MSDS/Industrial/10%25Hydr...
  - laythea 9y ago
    Thanks for the links. Seems like anyone in the right mind, would not deal with this, in anything other than a professional lab setting.
    - logfromblammo 9y ago
      Even then, you can only work with it in teams of at least 2, all being certified to work with HF, only during normal business hours, and with a safety checklist a mile long, which includes checking to see that the calcium gluconate in the emergency kit is unopened and unexpired, and there are extra gloves with it, so the person applying it to you does not also get poisoned just by touching you.
      - 9y ago
chaostheory 9y ago
> It's not just about safety for you, proper disposal of these chemicals is essential for the many generations to come. Yes Gordon Moore created a superfund site or two in California.
- ajross 9y ago
  Citation needed? The inorganic materials used in semiconductor fabrication, especially in the early days, tend to be fairly benign and are used only in small quantities relative to other industry. The HF monster everyone is talking about in this thread is dangerous only as a concentrated acid. It's highly soluble -- reduce it with a rainstorm or two and let it recombine to a neutral pH and you rapidly get to (literally!) toothpaste-level toxicity. There's a VERY serious discussion to be had about the safety for a backyard chip fabricator. But the idea that this is some kind of long term pollutant (relative to much more serious issues like the cleaning solutions in your very own closet!) is pretty spun. Edit: yeah, as the responses point out, the "superfund" sites in question are things like VOC contamination you see with any urban industry, nothing particular to semiconductor fabrication that would justify the upthread quote about contamination "for many generations to come".
  - TomV1971 9y ago
    Here is one of them: https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0902632 https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0... Intel graciously paid for trees to brighten up the street and has a nice street sign saying so. (It doesn’t say why they did.) This one is not directly related to silicon production, but the QA that came after.
  - mannykannot 9y ago
    No citation is needed when a simple internet search reveals plenty of references, and that the issue is not HF specifically - volatile organics are an important issue.
  - opencl 9y ago
    Intel superfund site #1: https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0901661 https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0... Intel superfund site #2: https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0901482 https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0... Intel superfund site #3: https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0902632 https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0...
jakeogh 9y ago
Nice HF technical overview: https://ehs.unc.edu/files/2015/09/hydrofluoricacid.pdf https://ehs.unc.edu/files/2015/09/hydrofluoricacid.pdf (tldr; nope; read it.) I needed to dissolve(ha!) fluorite once. You can get it started by adding a few drops of conc H2SO4 to your beautiful aqua regia solution. It goes deeper red, some happy bubbles appear, and as long as it stays put, makes it's own "aqua nasty"(pg88) as you gently add your powdered sample. I thought AQR+SA was called aqua nasty, but I cant get any hits other than this AA pdf with explicit HF added. Maybe an actual chemist can chime in, is there another name for the aqua regia +H2SO4 mix? https://archive-resources.coleparmer.com/Manual_pdfs/28750-10,-15.pdf https://archive-resources.coleparmer.com/Manual_pdfs/28750-1...
- smellf 9y ago
  From your link: INHALATION Estimates of the lowest lethal concentrations for hydrogen fluoride range from 50-250 ppm for 5-minute exposure and are based on accidental, ***voluntary*** and occupational exposure information. Someone volunteered to be exposed to this stuff??
- whitten 9y ago
  If I remember correctly in the book: "1636: The Chronicles of Dr. Gribbleflotz" he made "aqua regia" from "aqua fortis" and "acidum salis" I don't know if either of those were his name for aqua-regia + HydroSulphuric Acid. I know he called ethanol "aqua vitae" by repeatedly distilling wine. He also had "Oil of Vitriol" which he added to saltpeter to make "aqua fortis". He also talked about adding "Oil of Vitriol" to "aqua fortis" but doesn't say what it makes. I think maybe "oil of vitriol" was hydro sulfuric acid, but I am not sure. Perhaps you can find more or someone else can remember. (I used: https://www.ericflint.net/index.php/2016/06/03/1636-the-chronicles-of-dr-gribbleflotz-snippet-36/ https://www.ericflint.net/index.php/2016/06/03/1636-the-chro... to quote what I mentioned here.)
  - MrEldritch 9y ago
    Aqua regia is just the name for a mixture of nitric and hydrochloric acid which has the ability to dissolve gold. Aqua fortis was simply an archaic name for nitric acid; acidum salis (literally "salt acid") is likewise an old alchemical name for hydrochloric acid, rather straightforwardly named because it was an acid that was synthesized from salt. (If you ever see hydrochloric acid referred to as "muriatic acid", this is just a somewhat more modernized version of the same name: brine-y/salty acid.) Oil of vitriol is sulfuric acid. This was also quite a logical name at the time - it's an oily liquid that was made from vitriol (a common term for a class of brightly colored metal sulfate crystals). So, in the reaction given, when the sulfuric acid is added to saltpeter (potassium nitrate), the sulfate ion swaps places with the nitrate ion and you instead get nitric acid and potassium sulfate. Source: Have spent far, far too much time researching alchemical nomenclature because I thought it was cool.
nraynaud 9y ago
so he mentions piranha solution and you reflexively sercurinazi on the HF solution? Get a grip, there are turbo pumps, high vaccum and high voltage everywhere in the setup, don't reflexively repeat HF folklore it doesn't help anybody. Security is about what's really happening on the ground, not repeating folklore on a particularly trendy point.
phkahler 9y ago
>> For those considering exploring some of these steps in their own garage -- the chemistry is dangerous, perhaps HF in particular, as it doesn't hurt, it just kills you a few hours later. I was hoping that with 50 years of development behind us, the home fabricators could use less complex methods and less hazardous chemicals. In other words, can the folks who lived it help people like this by saying "If we had to do it over, I'd go about it like...." Any suggestions? If you had to reboot the chip fab business on a budget what would be a more practical approach?
- anoonmoose 9y ago
  There's just...no reason at all to do it for business purposes. If you're a prepper or looking for a science project I can understand it, it's a cool project. But from a business perspective you can buy the same thing but better for dollars and have it the next day.
  - kragen 9y ago
    The lowest-cost options I know of for commercial custom chip fabrication are MOSIS and CMP. Their pricing starts at €650 for 0.35 μm, but it's true that the result is much better. However, turnaround time is measured in weeks. You seem to be suggesting that there are options that are one order of magnitude faster and two orders of magnitude cheaper (but perhaps with a much coarser feature size). What are they?
- sevensor 9y ago
  I used to work in a fab. As far as I know, there's no acceptable way to remove native oxide without HF. We do have another etch process -- dry etch -- that uses plasma instead, but it causes surface damage, and you don't want that under the gate. Also, dry etch chambers are a lot more work to maintain than a fume hood where you do wet etch. Furthermore, dry etch has its own set of hazards, and you have to deal with a lot more potentially toxic vapor.
  - sevensor 9y ago
    Thinking a little more outside the box, you might look into using germanium instead of silicon. I don't know much about the germanium system, except that it supposedly grows less oxide. You're still going to have to deposit and remove oxide somehow, though, which means CVD reactors and silane. It's not going to be easy to get away from explosive toxic gases and dirty processes.
mozumder 9y ago
And then you have Phosphene gas used to dope silicon, where people have died changing empty supply tanks.
- sevensor 9y ago
  The exhaust lines on high-energy implanters (the ones that do P doping) are a treat. They get coated up with deposits of solid phosphorus. If accidentally exposed to atmosphere, they do what phosphorus does. We used to call it "unscheduled exhaust system PM." Medium and high current implanters where I worked accumulated arsenic in the exhaust system, but at least that doesn't explode on you.
Spooky23 9y ago
Thanks for saying this. I worked for a few years at a semiconductor fab r&d facility. (As a tenant) Seemingly everything associated with this stuff is toxic and polluting. The old timer war stories include stuff like accidental releases that stripped paint from all of the cars in the adjacent lot. Nasty stuff — the wisdom promoting garage stuff like this is questionable. :)
Cerium 9y ago
I'm here to second the recommendation to work, volunteer, or take a class at a university. I took a class on MEMS at my university, and for only a few hundred bucks got access to a fully stocked lab with proper training and supervision. It was a good experience I would recommend to anyone interested.
nightbrawler 9y ago
For those curious about the HF danger mentioned above, Wikipedia has an interesting (and scary) summary: https://en.wikipedia.org/wiki/Hydrofluoric_acid#Health_and_safety https://en.wikipedia.org/wiki/Hydrofluoric_acid#Health_and_s...
crankylinuxuser 9y ago
And I would argue that individuals have the right to commence with research and creation. Science is not 'easy stuff that harms nobody'. The Curies suffered radiological poisoning but furthered chemistry and physics a great deal. I would think that "computer science" has mollified people in thinking that science is painless, harmless venture of fun exploration. Go read up about the countless physicists and chemists who tried to crack fluorine. If you are a scientist, and not in a sciency-y setting (lab), have a laminated clipboard stating chemical threats, electrical threats, biogenic threats, and particulate threats. You may end up killing yourself. If you do, you did so in the name of science. Please, don't have others die because you failed to properly notify first responders of a threat.
Geee 9y ago
Besides IC fabrication, you can also use HF for making mouthwash: https://www.youtube.com/watch?v=gHoUCyQR7h8 https://www.youtube.com/watch?v=gHoUCyQR7h8

by ISL 9y ago

88e282102ae2e5b 9y ago

I understand why it's necessary, but I was shocked that he uses piranha in his home garage. I cannot echo the above sentiment enough.

deleted 9y ago
[deleted]

Itsdijital 9y ago

Good 'ole HF http://blogs.sciencemag.org/pipeline/archives/2004/03/03/things_i_wont_touch_1 http://blogs.sciencemag.org/pipeline/archives/2004/03/03/thi...

donpdonp 9y ago
TL;DR "hydrofluoric acid is a water solution of hydrogen fluoride, HF. That’s a gas, and it’s a lot worse. ... As soon as it hits anything moist – like your lungs – it dissolves in the water and turns into hydrofluoric acid again."
- lifeisstillgood 9y ago
  or "The straight liquid must really be a treat, but I’ve never seen it in that form, and would only wish to through binoculars."
  - AstralStorm 9y ago
    The fact that it is liquid at relatively balmy temperatures makes it a bit easier to handle than most gases, but then you better have great urethane seals, gloves and clothing everywhere. (Silicones are permeable, PTFE is damaged over time, nitrile and vinyl gloves also leak.)
    - jakeogh 9y ago
      8mil nitrile x2 with no extended(!) contact option. Like silane: http://amo-csd.lbl.gov/downloads/Chemical%20Resistance%20of%20Gloves.pdf http://amo-csd.lbl.gov/downloads/Chemical%20Resistance%20of%...
msla 9y ago
Oh, yeah. I knew someone would get around to linking to Derek Lowe and his inimitable "Things I Won't Work With" series. His best-known entry in that series, about chlorine triflouride, also has mention of HF and semiconductors: http://blogs.sciencemag.org/pipeline/archives/2008/02/26/sand_wont_save_you_this_time http://blogs.sciencemag.org/pipeline/archives/2008/02/26/san... > The compound also a stronger oxidizing agent than oxygen itself, which also puts it into rare territory. That means that it can potentially go on to “burn” things that you would normally consider already burnt to hell and gone, and a practical consequence of that is that it’ll start roaring reactions with things like bricks and asbestos tile. It’s been used in the semiconductor industry to clean oxides off of surfaces, at which activity it no doubt excels. > There’s a report from the early 1950s (in this PDF) of a one-ton spill of the stuff. It burned its way through a foot of concrete floor and chewed up another meter of sand and gravel beneath, completing a day that I’m sure no one involved ever forgot. That process, I should add, would necessarily have been accompanied by copious amounts of horribly toxic and corrosive by-products: it’s bad enough when your reagent ignites wet sand, but the clouds of hot hydrofluoric acid are your special door prize if you’re foolhardy enough to hang around and watch the fireworks Here's a video of some French people introducing the substance to things like a rubber glove and leather: http://blogs.sciencemag.org/pipeline/archives/2013/04/05/chlorine_trifluoride_some_empirical_findings http://blogs.sciencemag.org/pipeline/archives/2013/04/05/chl... TL;DW: FIRE!

jjeaff 9y ago

Of course, caution is always warranted when dealing with HF. However, I don't see any reason why it can't be safely used at home. In fact HF is found in lots of commonly used household cleaning products like rust and stain removers. Plenty of people are using Goof Off Rust remover and are not dropping dead later in the day.

deleted 9y ago
[deleted]
basicplus2 9y ago
Oh man.. you need to talk to those who have worked with the stuff.. The amount in household products is essentially zero and one drop of the pure stuff and you are gone.. this stuff is nightmare material, i know, i have worked with and around it. 70% pure accident.. PFF http://www.ehs.ucsb.edu/files/docs/ls/HF_fatality.pdf http://www.ehs.ucsb.edu/files/docs/ls/HF_fatality.pdf HTML http://www.geo.utexas.edu/geosafety/hf-accident.html http://www.geo.utexas.edu/geosafety/hf-accident.html 10% strength MSDS HTML http://www.kendon.com.au/Catalogue/MSDS/Industrial/10%25Hydrofluoricacid.htm http://www.kendon.com.au/Catalogue/MSDS/Industrial/10%25Hydr...
- laythea 9y ago
  Thanks for the links. Seems like anyone in the right mind, would not deal with this, in anything other than a professional lab setting.
  - logfromblammo 9y ago
    Even then, you can only work with it in teams of at least 2, all being certified to work with HF, only during normal business hours, and with a safety checklist a mile long, which includes checking to see that the calcium gluconate in the emergency kit is unopened and unexpired, and there are extra gloves with it, so the person applying it to you does not also get poisoned just by touching you.
    - 9y ago

chaostheory 9y ago

> It's not just about safety for you, proper disposal of these chemicals is essential for the many generations to come. Yes Gordon Moore created a superfund site or two in California.

ajross 9y ago
Citation needed? The inorganic materials used in semiconductor fabrication, especially in the early days, tend to be fairly benign and are used only in small quantities relative to other industry. The HF monster everyone is talking about in this thread is dangerous only as a concentrated acid. It's highly soluble -- reduce it with a rainstorm or two and let it recombine to a neutral pH and you rapidly get to (literally!) toothpaste-level toxicity. There's a VERY serious discussion to be had about the safety for a backyard chip fabricator. But the idea that this is some kind of long term pollutant (relative to much more serious issues like the cleaning solutions in your very own closet!) is pretty spun. Edit: yeah, as the responses point out, the "superfund" sites in question are things like VOC contamination you see with any urban industry, nothing particular to semiconductor fabrication that would justify the upthread quote about contamination "for many generations to come".
- TomV1971 9y ago
  Here is one of them: https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0902632 https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0... Intel graciously paid for trees to brighten up the street and has a nice street sign saying so. (It doesn’t say why they did.) This one is not directly related to silicon production, but the QA that came after.
- mannykannot 9y ago
  No citation is needed when a simple internet search reveals plenty of references, and that the issue is not HF specifically - volatile organics are an important issue.
- opencl 9y ago
  Intel superfund site #1: https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0901661 https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0... Intel superfund site #2: https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0901482 https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0... Intel superfund site #3: https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0902632 https://cumulis.epa.gov/supercpad/cursites/csitinfo.cfm?id=0...

jakeogh 9y ago

Nice HF technical overview: https://ehs.unc.edu/files/2015/09/hydrofluoricacid.pdf https://ehs.unc.edu/files/2015/09/hydrofluoricacid.pdf (tldr; nope; read it.) I needed to dissolve(ha!) fluorite once. You can get it started by adding a few drops of conc H2SO4 to your beautiful aqua regia solution. It goes deeper red, some happy bubbles appear, and as long as it stays put, makes it's own "aqua nasty"(pg88) as you gently add your powdered sample. I thought AQR+SA was called aqua nasty, but I cant get any hits other than this AA pdf with explicit HF added. Maybe an actual chemist can chime in, is there another name for the aqua regia +H2SO4 mix? https://archive-resources.coleparmer.com/Manual_pdfs/28750-10,-15.pdf https://archive-resources.coleparmer.com/Manual_pdfs/28750-1...

smellf 9y ago
From your link: INHALATION Estimates of the lowest lethal concentrations for hydrogen fluoride range from 50-250 ppm for 5-minute exposure and are based on accidental, ***voluntary*** and occupational exposure information. Someone volunteered to be exposed to this stuff??
whitten 9y ago
If I remember correctly in the book: "1636: The Chronicles of Dr. Gribbleflotz" he made "aqua regia" from "aqua fortis" and "acidum salis" I don't know if either of those were his name for aqua-regia + HydroSulphuric Acid. I know he called ethanol "aqua vitae" by repeatedly distilling wine. He also had "Oil of Vitriol" which he added to saltpeter to make "aqua fortis". He also talked about adding "Oil of Vitriol" to "aqua fortis" but doesn't say what it makes. I think maybe "oil of vitriol" was hydro sulfuric acid, but I am not sure. Perhaps you can find more or someone else can remember. (I used: https://www.ericflint.net/index.php/2016/06/03/1636-the-chronicles-of-dr-gribbleflotz-snippet-36/ https://www.ericflint.net/index.php/2016/06/03/1636-the-chro... to quote what I mentioned here.)
- MrEldritch 9y ago
  Aqua regia is just the name for a mixture of nitric and hydrochloric acid which has the ability to dissolve gold. Aqua fortis was simply an archaic name for nitric acid; acidum salis (literally "salt acid") is likewise an old alchemical name for hydrochloric acid, rather straightforwardly named because it was an acid that was synthesized from salt. (If you ever see hydrochloric acid referred to as "muriatic acid", this is just a somewhat more modernized version of the same name: brine-y/salty acid.) Oil of vitriol is sulfuric acid. This was also quite a logical name at the time - it's an oily liquid that was made from vitriol (a common term for a class of brightly colored metal sulfate crystals). So, in the reaction given, when the sulfuric acid is added to saltpeter (potassium nitrate), the sulfate ion swaps places with the nitrate ion and you instead get nitric acid and potassium sulfate. Source: Have spent far, far too much time researching alchemical nomenclature because I thought it was cool.

nraynaud 9y ago

so he mentions piranha solution and you reflexively sercurinazi on the HF solution? Get a grip, there are turbo pumps, high vaccum and high voltage everywhere in the setup, don't reflexively repeat HF folklore it doesn't help anybody. Security is about what's really happening on the ground, not repeating folklore on a particularly trendy point.

phkahler 9y ago

>> For those considering exploring some of these steps in their own garage -- the chemistry is dangerous, perhaps HF in particular, as it doesn't hurt, it just kills you a few hours later. I was hoping that with 50 years of development behind us, the home fabricators could use less complex methods and less hazardous chemicals. In other words, can the folks who lived it help people like this by saying "If we had to do it over, I'd go about it like...." Any suggestions? If you had to reboot the chip fab business on a budget what would be a more practical approach?

anoonmoose 9y ago
There's just...no reason at all to do it for business purposes. If you're a prepper or looking for a science project I can understand it, it's a cool project. But from a business perspective you can buy the same thing but better for dollars and have it the next day.
- kragen 9y ago
  The lowest-cost options I know of for commercial custom chip fabrication are MOSIS and CMP. Their pricing starts at €650 for 0.35 μm, but it's true that the result is much better. However, turnaround time is measured in weeks. You seem to be suggesting that there are options that are one order of magnitude faster and two orders of magnitude cheaper (but perhaps with a much coarser feature size). What are they?
sevensor 9y ago
I used to work in a fab. As far as I know, there's no acceptable way to remove native oxide without HF. We do have another etch process -- dry etch -- that uses plasma instead, but it causes surface damage, and you don't want that under the gate. Also, dry etch chambers are a lot more work to maintain than a fume hood where you do wet etch. Furthermore, dry etch has its own set of hazards, and you have to deal with a lot more potentially toxic vapor.
- sevensor 9y ago
  Thinking a little more outside the box, you might look into using germanium instead of silicon. I don't know much about the germanium system, except that it supposedly grows less oxide. You're still going to have to deposit and remove oxide somehow, though, which means CVD reactors and silane. It's not going to be easy to get away from explosive toxic gases and dirty processes.

mozumder 9y ago

And then you have Phosphene gas used to dope silicon, where people have died changing empty supply tanks.

sevensor 9y ago
The exhaust lines on high-energy implanters (the ones that do P doping) are a treat. They get coated up with deposits of solid phosphorus. If accidentally exposed to atmosphere, they do what phosphorus does. We used to call it "unscheduled exhaust system PM." Medium and high current implanters where I worked accumulated arsenic in the exhaust system, but at least that doesn't explode on you.

Spooky23 9y ago

Thanks for saying this. I worked for a few years at a semiconductor fab r&d facility. (As a tenant) Seemingly everything associated with this stuff is toxic and polluting. The old timer war stories include stuff like accidental releases that stripped paint from all of the cars in the adjacent lot. Nasty stuff — the wisdom promoting garage stuff like this is questionable. :)

Cerium 9y ago

I'm here to second the recommendation to work, volunteer, or take a class at a university. I took a class on MEMS at my university, and for only a few hundred bucks got access to a fully stocked lab with proper training and supervision. It was a good experience I would recommend to anyone interested.

nightbrawler 9y ago

For those curious about the HF danger mentioned above, Wikipedia has an interesting (and scary) summary: https://en.wikipedia.org/wiki/Hydrofluoric_acid#Health_and_safety https://en.wikipedia.org/wiki/Hydrofluoric_acid#Health_and_s...

crankylinuxuser 9y ago

And I would argue that individuals have the right to commence with research and creation. Science is not 'easy stuff that harms nobody'. The Curies suffered radiological poisoning but furthered chemistry and physics a great deal. I would think that "computer science" has mollified people in thinking that science is painless, harmless venture of fun exploration. Go read up about the countless physicists and chemists who tried to crack fluorine. If you are a scientist, and not in a sciency-y setting (lab), have a laminated clipboard stating chemical threats, electrical threats, biogenic threats, and particulate threats. You may end up killing yourself. If you do, you did so in the name of science. Please, don't have others die because you failed to properly notify first responders of a threat.

Geee 9y ago

Besides IC fabrication, you can also use HF for making mouthwash: https://www.youtube.com/watch?v=gHoUCyQR7h8 https://www.youtube.com/watch?v=gHoUCyQR7h8