5 ms·

X-rays could be used to cut down on problems bringing a new CPU to market

64 points by poiuz 10y ago

gliese1337 10y ago
The article doesn't make this clear, but this is an excellent example of an area where "pure research" and practical technology overlap. Free electron lasers are essentially particle accelerators (of the same sort used in, e.g., the LHC) with special configurations of magnets stuck on the end. They are large, expensive to build, and expensive to operate for essentially all the same reasons that research accelerators are. So advances in physics which lead to advances in accelerator technology, which allow further advances in pure physics, also directly impact the practicality of using FEL X-ray sources for imaging microchips (among other things).
- aylons 10y ago
  They aren't "essentially" particle accelerators, they are full-blown accelerators, linear accelerators, specifically.
oakwhiz 10y ago
Wouldn't this method also erase any EEPROMs on the die?
teddyh 10y ago
This could be useful to reverse-engineers who may want to do security verification (are there a hidden backdoors in this chip outside its specifications?) or to simply clone a chip outright.
deegles 10y ago
Pardon my ignorance, but would it be possible to use X-rays to read the contents of memory? Say, in a TPM or Secure Enclave? I feel like if you had an accurate enough beam you could detect if a memory cell is "charged" or not.
- anfractuosity 10y ago
  I'm not sure about whether you can do that with x-rays, however you might find this paper interesting - 'Reverse engineering Flash EEPROM memories using Scanning Electron Microscopy' - http://www.cl.cam.ac.uk/~sps32/cardis2016_sem.pdf http://www.cl.cam.ac.uk/~sps32/cardis2016_sem.pdf
  - ComputerGuru 10y ago
    Thank you for that relevant article and interesting read. I don't know why you're being downvoted, but I did my part to restore the balance.
- goldenkey 10y ago
  X-rays are ionizing radiation. You would just corrupt the fuck out of the memory.
- simias 10y ago
  I'm far from an expert on the subject but as far as I know you can only see the structure of the chip (how the transistors are wired together, basically), not the current state of the logic. So you can use this to dump a hardwired ROM but not dynamic content.
- ooqr 10y ago
  This isn't exactly what you asked for, but you might be interested in it anyway. https://arstechnica.com/gadgets/2013/02/ice-type-attacks-give-enemies-access-to-your-android-phones-data/ https://arstechnica.com/gadgets/2013/02/ice-type-attacks-giv...
astrodust 10y ago
I'm surprised lithography hasn't been replaced with something more nanoscale in origin like some kind of atomic deposition process where individual atoms are precisely bombarded onto the substrate to build up the features atom by atom. It would take longer to manufacture each chip, but if the machines to do the deposition were relatively cheap and simple to construct, they're not that far off of electron beams, the result could be a massively parallel manufacturing process.
- froindt 10y ago
  Current production seems very counterintuitive from a manufacturing/industrial engineering perspective. There are around 9 main processes and only about 3 add material. Depending on the chip design, it's probably going to 500-2000 manufacturing steps. That being said, each silicon wafer can hold up to hundreds of chips, making for a big batch. Going up to 18" wafers would make it even more appealing to stick with current methods of production. With how expensive all fab machines are, I don't see it becoming economical anytime soon for a complete overhaul of tooling.
- Dylan16807 10y ago
  "longer" is a bit of an understatement when lithography can sweep across a wafer at centimeters per second with nanometers of precision. Good luck ever finishing a single chip atom by atom.
  - astrodust 10y ago
    I'm presuming with the right control you can fire out millions of atoms per second, possibly more if you have multiple "guns". I'm not talking about dropping each into place with some kind of claw.
- deepnotderp 10y ago
  "Longer" if you're talking atom by atom is an understatement, you're going to almost never finish. Electron beams might be something relevant, but they're already being investigated. E-beam lithography is a thing, and as with all next-gen litho techniques, it too has its fair share of problems. For example, shot noise is a major problem which means that every time you halve your node, you're going to halve your throughput. This is devastating for semiconductor manufacturing, TSMC is already working double shifts trying to match demand. Also, the important thing to realize about semiconductors is that demonstrating something in the lab is a relatively easy ordeal, but making it mass manufacturable in a timely fashion with good yields is a herculean task. You can actually use X-ray litho for something more "nanoscale in origin" but it's really, REALLY difficult to make it in production.
ajross 10y ago
It's an article about a paper published in Nature about X-Ray tomography to image nm-scale features in modern ICs. And the only image presented in the whole article is a completely unrelated Chipworks die shot at about 10um per pixel.
kurthr 10y ago
Most of the problems with binging new digital ASICs to market have to do with the failure of -XRay-Lithography- EUV (now called Extreme UV) to provide fast enough exposures despite decades of development and billions in research investment. This is a hard problem, but quadruple patterning is also nasty and expensive at 7nm. Even if you can identify the error... if you can't make almost every one of a couple billion transistors correctly, you can't make a modern CPU. I'd recommend reading a few recent articles on the topic: The problem with lithography http://spectrum.ieee.org/semiconductors/devices/leading-chipmakers-eye-euv-lithography-to-save-moores-law http://spectrum.ieee.org/semiconductors/devices/leading-chip... A depressing conclusion https://www.hpcwire.com/2016/07/28/transistors-wont-shrink-beyond-2021-says-final-itrs-report/ https://www.hpcwire.com/2016/07/28/transistors-wont-shrink-b... An optimistic expert https://www.semiwiki.com/forum/content/6590-scott-jones-iss-talk-moores-law-lives.html https://www.semiwiki.com/forum/content/6590-scott-jones-iss-...
libeclipse 10y ago
> Essentially, it takes a very long time to obtain each pattern, and you need a lot of patterns. By the time you've finished imaging, management has brought you your golden watch. What does this last part about the golden watch mean? Is it a reference to retirement?
- doubleplusgood 10y ago
  Some companies gave out wristwatches commemorating significant tenures. There's even a Domino's Rolex.

64 points by poiuz 10y ago

The article doesn't make this clear, but this is an excellent example of an area where "pure research" and practical technology overlap. Free electron lasers are essentially particle accelerators (of the same sort used in, e.g., the LHC) with special configurations of magnets stuck on the end. They are large, expensive to build, and expensive to operate for essentially all the same reasons that research accelerators are. So advances in physics which lead to advances in accelerator technology, which allow further advances in pure physics, also directly impact the practicality of using FEL X-ray sources for imaging microchips (among other things).

aylons 10y ago
They aren't "essentially" particle accelerators, they are full-blown accelerators, linear accelerators, specifically.

oakwhiz 10y ago

Wouldn't this method also erase any EEPROMs on the die?

teddyh 10y ago

This could be useful to reverse-engineers who may want to do security verification (are there a hidden backdoors in this chip outside its specifications?) or to simply clone a chip outright.

deegles 10y ago

Pardon my ignorance, but would it be possible to use X-rays to read the contents of memory? Say, in a TPM or Secure Enclave? I feel like if you had an accurate enough beam you could detect if a memory cell is "charged" or not.

anfractuosity 10y ago
I'm not sure about whether you can do that with x-rays, however you might find this paper interesting - 'Reverse engineering Flash EEPROM memories using Scanning Electron Microscopy' - http://www.cl.cam.ac.uk/~sps32/cardis2016_sem.pdf http://www.cl.cam.ac.uk/~sps32/cardis2016_sem.pdf
- ComputerGuru 10y ago
  Thank you for that relevant article and interesting read. I don't know why you're being downvoted, but I did my part to restore the balance.
goldenkey 10y ago
X-rays are ionizing radiation. You would just corrupt the fuck out of the memory.
simias 10y ago
I'm far from an expert on the subject but as far as I know you can only see the structure of the chip (how the transistors are wired together, basically), not the current state of the logic. So you can use this to dump a hardwired ROM but not dynamic content.
ooqr 10y ago
This isn't exactly what you asked for, but you might be interested in it anyway. https://arstechnica.com/gadgets/2013/02/ice-type-attacks-give-enemies-access-to-your-android-phones-data/ https://arstechnica.com/gadgets/2013/02/ice-type-attacks-giv...

astrodust 10y ago

I'm surprised lithography hasn't been replaced with something more nanoscale in origin like some kind of atomic deposition process where individual atoms are precisely bombarded onto the substrate to build up the features atom by atom. It would take longer to manufacture each chip, but if the machines to do the deposition were relatively cheap and simple to construct, they're not that far off of electron beams, the result could be a massively parallel manufacturing process.

froindt 10y ago
Current production seems very counterintuitive from a manufacturing/industrial engineering perspective. There are around 9 main processes and only about 3 add material. Depending on the chip design, it's probably going to 500-2000 manufacturing steps. That being said, each silicon wafer can hold up to hundreds of chips, making for a big batch. Going up to 18" wafers would make it even more appealing to stick with current methods of production. With how expensive all fab machines are, I don't see it becoming economical anytime soon for a complete overhaul of tooling.
Dylan16807 10y ago
"longer" is a bit of an understatement when lithography can sweep across a wafer at centimeters per second with nanometers of precision. Good luck ever finishing a single chip atom by atom.
- astrodust 10y ago
  I'm presuming with the right control you can fire out millions of atoms per second, possibly more if you have multiple "guns". I'm not talking about dropping each into place with some kind of claw.
deepnotderp 10y ago
"Longer" if you're talking atom by atom is an understatement, you're going to almost never finish. Electron beams might be something relevant, but they're already being investigated. E-beam lithography is a thing, and as with all next-gen litho techniques, it too has its fair share of problems. For example, shot noise is a major problem which means that every time you halve your node, you're going to halve your throughput. This is devastating for semiconductor manufacturing, TSMC is already working double shifts trying to match demand. Also, the important thing to realize about semiconductors is that demonstrating something in the lab is a relatively easy ordeal, but making it mass manufacturable in a timely fashion with good yields is a herculean task. You can actually use X-ray litho for something more "nanoscale in origin" but it's really, REALLY difficult to make it in production.

ajross 10y ago

It's an article about a paper published in Nature about X-Ray tomography to image nm-scale features in modern ICs. And the only image presented in the whole article is a completely unrelated Chipworks die shot at about 10um per pixel.

kurthr 10y ago

Most of the problems with binging new digital ASICs to market have to do with the failure of -XRay-Lithography- EUV (now called Extreme UV) to provide fast enough exposures despite decades of development and billions in research investment. This is a hard problem, but quadruple patterning is also nasty and expensive at 7nm. Even if you can identify the error... if you can't make almost every one of a couple billion transistors correctly, you can't make a modern CPU. I'd recommend reading a few recent articles on the topic: The problem with lithography http://spectrum.ieee.org/semiconductors/devices/leading-chipmakers-eye-euv-lithography-to-save-moores-law http://spectrum.ieee.org/semiconductors/devices/leading-chip... A depressing conclusion https://www.hpcwire.com/2016/07/28/transistors-wont-shrink-beyond-2021-says-final-itrs-report/ https://www.hpcwire.com/2016/07/28/transistors-wont-shrink-b... An optimistic expert https://www.semiwiki.com/forum/content/6590-scott-jones-iss-talk-moores-law-lives.html https://www.semiwiki.com/forum/content/6590-scott-jones-iss-...

libeclipse 10y ago

> Essentially, it takes a very long time to obtain each pattern, and you need a lot of patterns. By the time you've finished imaging, management has brought you your golden watch. What does this last part about the golden watch mean? Is it a reference to retirement?

doubleplusgood 10y ago
Some companies gave out wristwatches commemorating significant tenures. There's even a Domino's Rolex.