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Science Technology

Ohm's Law Survives To the Atomic Level 104

Posted by samzenpus
from the smaller-the-better dept.
Hugh Pickens writes "Moore's Law, the cornerstone of the semiconductor industry, may get a reprieve from its predicted demise. As wires shrink to just nanometers in diameter, their resistivity tends to grow exponentially, curbing their usefulness as current carriers. But now a team of researchers has shown that it is possible to fabricate low-resistivity nanowires at the smallest scales imaginable by stringing together individual atoms in silicon as small as four atoms (about 1.5 nanometers) wide and a single atom tall. The secret is to introduce phosphorus along that line because each phosphorus atom donates an electron to the silicon crystal, which promotes electrical conduction. They then encase the nanowires entirely in silicon, which makes the conduction electrons more immune to outside influence. By embedding phosphorus atoms within a silicon crystal with an average spacing of less than 1 nanometer, the team achieved a diameter-independent resistivity, which demonstrates ohmic scaling to the atomic limit. 'That moves the wires away from the surfaces and away from other interfaces,' says physicist says Michelle Simmons. 'That allows the electron to stay conducting and not get caught up in other interfaces.' The wires have the carrying capacity of copper, indicating that the technique might help microchips continue their steady shrinkage over time and may even extend the life of Moore's Law. 'Fundamentally, we have shown that we can maintain low resistivities in doped silicon wires down to the atomic scale,' says Simmons, adding that it may not be ready for production now, but, 'who knows 20 years from now?'"
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Ohm's Law Survives To the Atomic Level

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  • ohmigod (Score:5, Funny)

    by alphatel (1450715) * on Friday January 06, 2012 @09:10AM (#38608580)
    If the atomic resistance gather together at ohm's law, will they occupy it?
  • At first I was thinking they meant Moore's Law and somebody had found a way to make really tiny ultra fast processors. Moore, Ohm, Watt... learned all of their laws in the same class in high school. I really need to take up drinking coffee in the morning.

    • Re:So many laws (Score:5, Insightful)

      by jpapon (1877296) on Friday January 06, 2012 @09:38AM (#38608756) Journal
      You learned Moore's "law" in high school physics class? That seems pretty off-topic to me.
      • Re: (Score:1, Insightful)

        by Anonymous Coward

        You do realize the entire semi conductor field is one giant application of physics and electrical engineering right?

        The dudes making these newer chips have to have a pretty good understanding of the physics. They have to understand what their electrical components will do at the scales they are using and why they are or are not getting the performance they expect.

        So I could totally see a physics teacher bringing up Moores law. It is fairly relevant to what sorts of things the students may be working on if

      • Actually I learned Ohm's law in a high school computer/networking class. Never got around to taking physics.

  • But will... (Score:4, Insightful)

    by blahplusplus (757119) on Friday January 06, 2012 @09:23AM (#38608656)

    ... it scale and can you produce it cheaply?

    • Re:But will... (Score:5, Insightful)

      by fuzzyfuzzyfungus (1223518) on Friday January 06, 2012 @09:26AM (#38608670) Journal
      It is pretty much assured that it will scale better and cost less than all those effects for which the fundamental physics don't actually work, so we are off to an atypically promising start...
      • Re: (Score:3, Funny)

        by captainpanic (1173915)

        You are such a pessimist, saying that in order to make money, something should actually keep to the laws of fundamental physics.

        That was meant as a sarcastic joke, but while writing it down, I fear it might actually be true. There are plenty of scams out there.

    • It is doped silicon, like nearly any semiconductor out there, so it won't face the problems of increasing the number of steps and different substances in fabs.

      But it is still a very precise fabrication. Big fabs aren't up to the task, so expect at least a decade before that gets mainstream.

    • by calgar99 (856142)
      More importantly, will it blend?
    • by Matheus (586080)

      ...about 20 years...

      Obligatory XKCD reference (Happy 1000'th birthday XKCD!)

      http://xkcd.com/678/ [xkcd.com]

  • So the Star Trek prediction where computers of the future seem to be full of brightly lit crystals may have been accurate?
  • by Patron (2242336) on Friday January 06, 2012 @09:28AM (#38608688)
    Of course it's valid. It's a law! Not some phony-baloney "theory" like evolution or gravity.
  • by shoemakc (448730) on Friday January 06, 2012 @09:29AM (#38608694) Homepage

    Hate to have to solder one :-)

  • Could be very useful (Score:5, Interesting)

    by Covalent (1001277) on Friday January 06, 2012 @09:30AM (#38608704)
    TFA says that the wires were deposited lithographically (the technique currently used to make chips) and then the phosphorus was deposited. So this, in theory, could be done cheaply.
    However, TFA also mentions low temperature. It doesn't measure exactly what temperature, but processors are not usually operated at low temperatures. If this is a "liquid nitrogen cold" temperature, then this could very well be useless on a grand scale. But if the effect survives to room temperature (or higher), then this could have a huge impact.
    Just a first order approximation would show that these wires are about 5 times smaller than the current 22nm state-of-the-art. In two dimensions, that means roughly a 2500% increase in density, enough to keep Moore's law alive and well for some time to come.
    • by jpapon (1877296) on Friday January 06, 2012 @09:50AM (#38608848) Journal
      If it's liquid nitrogen cold, wouldn't it make more sense to just use a high temperature superconducting material? I wonder if nanoscale wires made from something like TBCCO would still be superconducting? I don't see why they wouldn't, but I also am not really knowledgeable in the subject area.
      • by jpapon (1877296) on Friday January 06, 2012 @09:53AM (#38608868) Journal
        Nevermind, superconducting crystals are way too complicated to make nanoscale wires from.
    • In two dimensions, that means roughly a 2500% increase in density, enough to keep Moore's law alive and well for some time to come.

      Except that fabricating wires isn't quite the same as fabricating transistors.

  • by NReitzel (77941) on Friday January 06, 2012 @09:33AM (#38608726) Homepage

    The resistance of interconnects grows polynomially, not exponentially, as they decrease in size.

    It's an important difference. As sizes get small enough, we start to see stochastic effects, but we're not there yet.

    • I think they're using the word "exponential" in the colloquial sense to mean "it gets more and more and more!!!", rather than in the precise mathematical sense.
    • by The Creator (4611)

      Don't you mean hyperbolically?

    • by Anonymous Coward

      Even more precisely the article talks about resistivity not resistance. Resistivity is the property of an Ohmic material (in the macro sense) and is temperature dependent to some degree. Resistance is the ratio of the voltage across a component to the current through the component and for a device made of Ohmic material is a function of the resistivity and geometry of the device.

      I believe there have been experiments that show that the resistivity (not resistance) at quantum scales is not only temperature

    • by jbengt (874751)

      The resistance of interconnects grows polynomially, not exponentially, as they decrease in size.

      I'm not sure if they used the term exponentially correctly or not, but they did not say that a wire's resistance grows as wires get thinner (that wouldn't exactly be news, even for Slashdot), but that a wire's resistivity increases as (very thin) wires get thinner.

  • Now we have to worry about shrinkage? Maybe the microchip was in the pool

  • by marcosdumay (620877) <marcosdumay@gmai l . c om> on Friday January 06, 2012 @10:32AM (#38609242) Homepage Journal

    The wires are composed of doped silicon, and features of doped silicon are at least several atoms big. It may be made of bunch of atoms of dopants, but they are embebed on a crystal dozens of atoms wide. Also, the wires ccertanly an't work without those dozens of atoms, and another wire can't be as close to share some of those atoms without being connected. For all practical porposes, the wire is dozens of atoms wide.

    Why can't /. just anounce a semiconductor breakthrough for what it is? "Smaler wire made of silicon" would make it, for exemple.

    And, by the way, Ohm's law holds at the atomic level as well as it holds for big conductors. People learned that by studying organic conductors ages ago. The problem is how to make silicon work the same way. That is what TFA seems to be about (don't really know because it is behind a pay wall).

    • by Anonymous Coward

      Being embedded within the silicon, as opposed to being constrained to a surface, would seem to allow the potential for a 3d scaffolding of connections within a block of silicon. The space lost to requiring its embedding might be made up for by the embedding itself.

  • Nano-insulated wire? (Score:4, Interesting)

    by Muad'Dave (255648) on Friday January 06, 2012 @10:32AM (#38609244) Homepage

    It sounds like they've created nano-scale insulated wire, kinda like myelin-coated nerve fibers.

    • by Anonymous Coward

      No. The scale is a hell of a lot smaller. And insulated nanowires is nothing new. What's exciting here is that the wire is ~1.5nm in diameter and that the physics works out to give a linear relationship between resistance and length.

      This isn't exactly a breakthrough. Nobody is saying that these processes will be used industrially. Instead it's part of a foundation that lets us understand how to make better devices and tests our understanding of the physics. The group that made these works on quantum computi

  • "which makes the conduction electrons more immune to outside influence" How can something be more or less immune than another?
  • The simple translation of this article is:
    "We made really bad nanowires."

    All that's necessary to demonstrate this effect is to create a system with enough defects and scattering (aka doping) to make scattering based resistance much larger than quantum resistance. This isn't something I thought was still under debate.

If I have seen farther than others, it is because I was standing on the shoulders of giants. -- Isaac Newton

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