Ohm's Law Survives To the Atomic Level 104
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?'"
ohmigod (Score:5, Funny)
Re: (Score:2)
Re:Make your mind up! (Score:5, Informative)
They're different laws about different things, they just happen to relate in this instance.
Re: (Score:3)
Re: (Score:1)
Little known fact about Ohm - he is also the inventor of the mantra.
(Ohm... ohm...)
-ducks airborne tomatoes-
So many laws (Score:2)
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)
Re: (Score:1, Insightful)
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
Re: (Score:3)
Actually I learned Ohm's law in a high school computer/networking class. Never got around to taking physics.
Re: (Score:2)
On the one hand, instead of physics I took classes in computer networking which I now do as a career. I really don't think I missed much as I haven't needed to calculate trajectories in a few years.
On the other hand, while physics was optional, French was not. And that my friend, is what's screwed up with the American education system.
Re:Just a rant (Score:4, Insightful)
Since the popular definition of Moore's Law is exponential growth in any tech-related field, I'd say approximately never..
Re: (Score:1)
Re: (Score:1)
The misrepresentation of what Moore actually said is the bigger problem for me. All this "exponential growth" crap isn't part of Moore's law. Nor is it about any other technology. It would be used a lot less if the "geeks" around here would keep Moore's Law to what Moore really said.
I'm not surprised in some ways though. A couple of years ago there was an IEEE podcast of some professor giving a lecture about the near-future problems in the EE field in relation to processing power. Even there he had
Re: (Score:2)
You don't have to be technically correct when repeating moors law because moors law isn't technical... or even a real law. It's just a guideline the industry grabbed on to as a way to time their delayed release cycle for maximum profitability.
Re: (Score:2, Informative)
exponential growth
y=x(1+r)^t
where x is the starting value, r is the rate of growth (doubling = 100% = 1) and t is a discrete interval (1 = 18 months, 2 = 36 months, etc)
given a starting value of 1000, after 18 months, it doubles.
y = 1000(1+1)^1 = 1000(2) = 2000
after 36 months, it doubles again
y = 1000(1+1)^2 = 1000(4) = 4000
after 54 months, it doubles again
y = 1000(1+1)^3 = 1000(8) = 8000
after 72 months, it doubles again
y = 1000(1+1)^4 = 1000(16) = 16000
this is a straight out of the textbook definition of e
Re: (Score:2)
My fault I guess, I was still under the impression it still uses the 'processor speed doubles every 18 months' definition (which isn't really exponential, but I will go with the flow).
US scholar Albert Bartlett pointed out the difficulty to grasp ramifications of exponential growth, stating: "The greatest shortcoming of the human race is our inability to understand the exponential function."
Don't beat yourself up too much, it's apparently REALLY hard to understand.
Re: (Score:2)
So what is exponential growth then? Given you just dismissed the textbook definition as not being "really exponential".
Re: (Score:1)
Look at this chart [wikipedia.org] here, from the wiki [wikipedia.org] on Moore's Law -
and compare it to this one [wikipedia.org] here, from the wiki on Exponential Growth (specifically the green line) -
Looks to me like the growth in the Moore's Law chart is linear (in layman's terms = a smooth, steady incline), rather than exponential (again, in layman's terms = a steep increase after a smooth incline).
Does it match the textbook definition? Perhaps not. But it passes the smell test to me.
Re: (Score:2)
Re: (Score:2)
Re: (Score:1)
The Y axis on the Moore's law is distorted to make the resulting line linear.
Re: (Score:2)
Except that axis of the Transistor count are already given in exponential order. So, yet it is exponential growth.
Re: (Score:2)
If you want to see the algebra, if log y = a t (log is a linear function for some constant a), the e^(log y) = y = e^(a t), the exponential, where the particular log function I'm using (there is one for each possible ba
Re: (Score:2)
It's exponential if your counting in binary.
Re: (Score:2)
It certainly is exponential. Although that's not actually Moore's law, what you stated is exponential.
P = T^2
Where P=Processor power, and T=Time expressed in 18 month units. 2 is the exponent, which makes it "exponential."
Re: (Score:1)
Re: (Score:2)
P = 2^T
i.e. a doubling every 18 months: 1 2 4 8 16
Re:Just a rant (Score:5, Funny)
At what point will we stop hearing about it?
When you stop reading a site dedicated to geeks, computer professionals and computer enthusiasts.
Re:Just a rant (Score:5, Funny)
Well, fair enough, but what about Slashdot?
Re: (Score:3)
My only issue with Moore's law is that it's a "Law", when really it's more of a guideline. If it was truly a law, then semiconductors would half in size naturally over time, without any research or development involved. Plus I believe that the "Law" gets regularly adjusted as the trend declines.
Re: (Score:2)
"Law" is being used ironically. It's really not even a guideline, just one man's observation. It has become self-fulfilling, since companies plan their products around it - so it will continue until no longer possible IMHO.
Moore never adjusted his "law", though other Intel executives sometimes refer to the time as 18 months instead of 2 years.
Re: (Score:3)
I think everyone understands Moore's law is not a law in the scientific sense, but rather a Coloquialism like "Murphy's law".
It also somewhat useful. It lets us make some basic assumptions like, ok I have W data today, the volume grows at rate X/year, it takes Y machines to handle that today, and based on Y doubling in capacity every 18 months or so I will need Z machines for the future state. Can I continue to scale like this?
Is it accurate, precise, or grounded in solid facts no but its still a nice rul
Re: (Score:3)
Re: (Score:2)
"I think everyone understands Moore's law is not a law in the scientific sense, but rather a Coloquialism like "Murphy's law"."
First of all. I'd caution you to show more respect to Mr. Murphy. Second Moore's law became a self fulfilling prophecy the minute the major chip development companies heard it. It's a way of colluding without breaking the law. Got a technology that can give a 10 fold increase, another that could give 2 fold, and another that could give 4 fold... all in the research lab of course so
Re: (Score:2)
Exactly, the reason we hear about it is that chip companies decided it was a decent way to space out their releases. Develop tech that gives an 8 fold increase in transistors? Don't need to work that to release immediately, focus on tech giving only a two fold increase or watered down step along the path of the 8 fold increase and get that ready for production. That way you already know where to go from there.
Re: (Score:3)
Re:Just a rant (Score:5, Funny)
Isn't the first law of Thermodynamics that you don't talk about Thermodynamics?
Re:Just a rant (Score:5, Interesting)
Likely because I just quit smoking and are somewhat grumpy, but I am tired of hearing about Moore's Law. Maybe those in the semiconductor industry care about it, but I, and those I work with certainly don't. At what point will we stop hearing about it? /rant
(Thank you for your patience. Now where are the damn pretzels?)
The most important part of Moore's Law was it essentially saying that your new toy will be far better than your old one before it even breaks. When the rate of doubling gets closer to 10 years, buying a new computer isn't going to be so much as the new toy is faster but rather the old toy broke. Once that driving force is over with, electronic companies will be talking about other ways to produce money in more mundane ways.
Re: (Score:2)
Nah, they just won't measure the performance of a computer in terms of chip anymore. There are plenty of specs they can use to convince the average idiot that the new pc is the bigger better one and the old one sux0rs.
Re: (Score:2)
The most important part of Moore's Law was it essentially saying that your new toy will be far better than your old one before it even breaks.
I wouldn't put it that way, because then you get into the messy part of whether a 2 GHz computer is twice as good as a 1 GHz computer, not just twice as fast. Honestly, computers have scaled faster than I've been able to scale my use for them. My upgrades are increasingly a matter of luxury rather than need. You can always say you will find new uses, but it's not like people are going to stop listening to music because playing music takes 0.1% CPU power. Or watching HD movies for that matter, now that we ha
Re: (Score:2)
The most important part of Moore's Law was it essentially saying that your new toy will be far better than your old one before it even breaks. When the rate of doubling gets closer to 10 years, buying a new computer isn't going to be so much as the new toy is faster but rather the old toy broke. Once that driving force is over with, electronic companies will be talking about other ways to produce money in more mundane ways.
Yeah, they'll actually have to make their software run efficiently.
Re:Just a rant (Score:5, Funny)
Re: (Score:2)
1.5 yr is not 1 yr or so. If anything it'd be 2 yrs or so since it rounds up.
But will... (Score:4, Insightful)
... it scale and can you produce it cheaply?
Re:But will... (Score:5, Insightful)
Re: (Score:3, Funny)
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.
Re: (Score:2)
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.
Re: (Score:1)
Re: (Score:2)
...about 20 years...
Obligatory XKCD reference (Happy 1000'th birthday XKCD!)
http://xkcd.com/678/ [xkcd.com]
Encased in silicon crystal (Score:1)
Re:Encased in silicon crystal (Score:5, Informative)
This just in from a GOP spokesperson: (Score:5, Funny)
Re:This just in from a GOP spokesperson: (Score:4, Funny)
Heres a question to ask the Republican candidates for President:
If elected will you repeal Moore's Law?
(Unfortunately Herman Caine is no longer in the race, because he would probably repeal Cole's Law (after all thats served with KFC, not Godfathers
pizza)
Hot Iron and a Steady Hand... (Score:5, Funny)
Hate to have to solder one :-)
Could be very useful (Score:5, Interesting)
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.
Re:Could be very useful (Score:4, Interesting)
Re:Could be very useful (Score:4, Insightful)
Re: (Score:2)
Re: (Score:1)
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.
Let's be precise here,.. (Score:5, Informative)
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.
Re: (Score:1)
Re: (Score:2)
Don't you mean hyperbolically?
Re: (Score:1)
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
Re: (Score:2)
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.
Re:Ohm's Law (Score:5, Funny)
Coles Law is my favorite.
Yummy.
Re: (Score:2)
Groan.
Re: (Score:1)
I got it just before I searched for Cole's Law on Wiki. Groan.
Then I decided to search for it anyway on the off hand chance there actually was a Cole's Law, and it just redirects me to coleslaw. Seems even Wiki is in on the joke!
(Something tells me this may be an old gem somewhere. If the internet is good for something it's recycling old jokes on new audiences...)
Microchip shrinkage? (Score:2)
Now we have to worry about shrinkage? Maybe the microchip was in the pool
Not exactly "atomic level" (Score:5, Interesting)
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).
Re: (Score:1)
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)
It sounds like they've created nano-scale insulated wire, kinda like myelin-coated nerve fibers.
Re: (Score:1)
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
Immune? (Score:1)
translation (Score:2)
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.
Re: (Score:2)