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Intel Hardware Technology

Intel: Metal in Future Chips = Less Leakage (updated) 240

Posted by timothy from the future-tech dept.
securitas writes "Intel is contemplating using metal instead of silicon in future chips for the 'transistor gate, which controls whether a transistor is on or off' and the 'dielectric, an insulating layer below the gate,' which are respectively made of silicon atoms and silicon dioxide. 'Millions of minuscule switches that make up silicon chips leak electricity when they're supposed to be shut off. To compensate, engineers have increased the current, driving up power consumption, decreasing battery life for portable devices and generating more heat.' AMD has also experimented with metal instead of silicon. By moving to metal AMD and Intel expect to reduce electricity leakage. More from AP via SeattlePI and the Miami Herald." Update: 11/05 15:25 GMT by T : Read on below for some information from Intel on why this is a good thing.

gManZboy writes "Following up on the Intel news that about using metal in chips -- here's an explanation from Shekhar Borkar (Intel Research Fellow) about why heat, power, and sub-threshold leakage, not transistor size, are the real challenges to Moore's law. Apparently, in order to make chips much faster, we're going to have to pump more electricity in then anything else in our houses -- and they'll soon be as hot as a nuclear reactor -- no, really."
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Intel: Metal in Future Chips = Less Leakage (updated) More

Intel: Metal in Future Chips = Less Leakage (updated)

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  • Which metal? (Score:3, Interesting)

    by msgmonkey ( 599753 ) on Wednesday November 05, 2003 @09:47AM (#7396109)
    I dont see any mention of the type of metal that would be most suitable. I'm sure all metals are n't created equal.

    • Re:Which metal? (Score:5, Informative)

      by MikeD83 ( 529104 ) on Wednesday November 05, 2003 @09:50AM (#7396139)
      In the AMD article the use of Nickel is mentioned.

    • Re:Which metal? (Score:2, Interesting)

      by dustinmarc ( 654964 )
      It's a secret. Intel isn't saying what the material is, just that they've discovered a probable solution to fix the achilles heel of the chipmaking industry.

      Basically, they are saying that they have found two new materials with a high k dielectric that reduces current leakage by more than a 100 times silicon dioxide and hopefully plan to use it by 2007 in production. They also have tested the materials and had excellent results in a lab environment. Still, they are being vague on the details, and who c

    • Re:Which metal? (Score:5, Informative)

      by Cougar1 ( 256626 ) on Wednesday November 05, 2003 @11:39AM (#7397205)
      I dont see any mention of the type of metal that would be most suitable. I'm sure all metals are n't created equal.

      Actually, two types of metal are probably needed. One for nmos transistors and another for pmos transistors. Nmos and pmos transistors have different threshold voltages (the voltage at which the device turns on), but ideally you would like both types of transistors to switch at the same voltage. The threshold voltage of a device can be shifted by modifying the "workfunction" of the gate metal. The workfunction is the energy required to remove an electron from the metal surface.

      One reason polysilicon gates are used in conventional CMOS is that the workfunction of polysilicon can be modified by changing the level of doping and the type of dopant material (usually B, P or As). Thus, polysilicon gates can be used for both nmos and pmos transistors and by varying the doping, both types of devices can have the same threshold voltage.

      Shifting the workfunctions of metals, using dopants is not so straightforward. As a result it will probably be necessary to use two different metals having different workfunctions for nmos and pmos transistors. Further complicating matters is the fact that the gate metal can interact with the dielectric material, modifying the effective workfunction and thus the threshold voltage. So, while the isolated metal may have the necessary workfunction, the workfunction may shift when the metal is part of a device. Thus, a lot of testing and experimentation is needed to find a metal that has the proper workfunction after it has been put into a device.

    • Re:Which metal? (Score:3, Informative)

      by geekee ( 591277 )
      Yes, the type of metal is important due to the workfunction of the metal. This determines the potential interactions between the semiconductor and the metal, which affects things like device threshold voltage.

  • Heh (Score:2, Insightful)

    by rwiedower ( 572254 )
    The changes are largely necessary because of the unsavory consequences of Moore's Law, the famous dictum that states that the number of transistors on a chip doubles every two years. Yeah, it's all that pesky "Moore's Law" fault...
    • They didn't even get it right, isn't it 18 months?

    • From Intel's site... (Score:5, Informative)

      by sczimme ( 603413 ) on Wednesday November 05, 2003 @10:01AM (#7396245)

      The history of Moore's Law. [intel.com]

      Or if you are interested in Moore's original paper, you can find it here [intel.com].

    • The changes are largely necessary because of the unsavory consequences of Moore's Law, the famous dictum that states that the number of transistors on a chip doubles every two years

      Moore's Law is only an empircal observation -- a convenient curve that fits through the our current data on time and transistor count. There are no gaurantees that this trend will hold for the future.

      The point is that no physical phenomena forces the doubling. At best, one could say that mental and procedural limits preve
      • Moore's Law is a market imperative, which to a business is pretty much the same thing as a law.
        • Moore's Law is a market imperative, which to a business is pretty much the same thing as a law.

          Interesting insight. I wonder if there is an accidental collusion among semiconductor companies to limit their progress to Moore's observed trend? It seems suspicious to me that the trend should continue for so long without an obvious physical cause. In my orginal post, I suggested that mental and procedural limits kept companies for doubling faster than Moore's Law -- people just don't seem to create magic

    • Re:Heh (Score:3, Insightful)

      by Alien54 ( 180860 )
      Apparently, in order to make chips much faster, we're going to have to pump more electricity in then anything else in our houses -- and they'll soon be as hot as a nuclear reactor -- no, really.

      This makes sense, even from the view point on increasing density and complexity of data alone being packed into smaller and smaller containers. Even if you only allocated 1 electron per bit, after a while all of those bits start to add up. Unless you go to another system.

      As an example, people often cite the human

  • Metal Implants? (Score:5, Funny)

    by telstar ( 236404 ) on Wednesday November 05, 2003 @09:49AM (#7396121)
    Man, and here I thought silicon felt weird.

  • Copper? (Score:2, Insightful)

    by Anonymous Coward
    I swear I remember IBM moving to copper for chips a while back (C.2-3 years ago). Was it for production chips or just R&D purposes?

    Is this just a question of Intel playing catch-up?

    • Re:Copper? (Score:5, Informative)

      by msgmonkey ( 599753 ) on Wednesday November 05, 2003 @09:55AM (#7396184)
      You are thinking of the Copper traces instead of Aluminium, the transistors remained Silicon. Here they are talking about metal transistors.

      • Re:Copper? (Score:4, Informative)

        by DarthTaco ( 687646 ) on Wednesday November 05, 2003 @10:59AM (#7396816)
        You are thinking of the Copper traces instead of Aluminium, the transistors remained Silicon. Here they are talking about metal transistors.

        Not true at all. The copper in IBM's process is for interconnects, not traces. I'm not sure what metal they use for the traces, but it's probably aluminum and definitely not copper. The connection between layers (interconnect) are copper plugs.

        The metal intel is talking about is strictly for the gate terminal connection of the transistor. The transistor is still doped silicon or gallium arsenide or whatever semiconductor they are using.
      • And the entire industry has adopted copper for interconnect in modern processes, not just IBM.
    • Here [a1-electronics.net] is an article explaining low-k dielectric. I believe this is a shipping product on the Power4/4+ [ibm.com] based systems and it is in the EXA chipset [ibm.com] on the x365/x440/x445/x450 Intel servers, and the Apple G3 [macworld.com] and G5 [apple.com]. The xSeries products even have little copper BB's in the grill of the system to symbolize that they use copper based technology.
      • Different subject. Up in the metal interconnect layers, you want low-K to reduce capacitance between unrelated signals. Down at the gate level, you want high-K dielectrics to make it possible to induce a reasonable channel charge at low voltages and practical gate thicknesses.
  • Yeah, I hate it when my silicon breaks and creates leakage.

  • Metal dielectric!? (Score:5, Funny)

    by CaptainAlbert ( 162776 ) on Wednesday November 05, 2003 @09:51AM (#7396150) Homepage
    I have no trouble understanding a switch from poly to metal for gate connections... but a metal dielectric? That seems to run counter to common sense. The dielectric is, by definition, required to be an insulator, whereas metals, also by definition, conduct electricity rather well. What is this magic substance?

    I love this site sometimes - where else can you post completely clueless questions and be virtually guaranteed to get an intelligent response from at least two people with PhDs in semiconductor physics? :-)
    • where else can you post completely clueless questions and be virtually guaranteed to get an intelligent response from at least two people with PhDs in semiconductor physics?

      Included in this great package are at least a dozen unintelligent responses coming from people who think they have PHD's in BS.

    • <blockquote>I love this site sometimes - where else can you post completely clueless questions and be virtually guaranteed to get an intelligent response from at least two people with PhDs in semiconductor physics? :-)</blockquote>

      What you meant to say was that you're virtually guaranteed to get a clueless response from at least two people claiming to have a PhD in semiconductor physics. :-) Right?

    • Re:Metal dielectric!? (Score:3, Interesting)

      by brassman ( 112558 )
      A metal dielectric does sound like voodoo... but at the scale they're describing -- four ATOMS thick!? -- I suspect it's more of a waveguide (or perhaps a forcefield) than a physical barrier.
    • The dielectric is, by definition, required to be an insulator, whereas metals, also by definition, conduct electricity rather well

      Perhaps they are using some kind of unobtanium alloy with phlogiston repelant properties

    • "With one new material -- known as a ``high k dielectric'' for its ability to hold a charge -- leakage is greatly reduced. In Intel's tests, the material -- whose composition the company would not reveal -- is thicker than silicon dioxide, but engineers say it will be shrunk."

      The dielectric isn't metal, it's something else.

    • Re:Metal dielectric!? (Score:2, Interesting)

      by Drakin ( 415182 )
      Well, if I recall correctly, tantalum oxide is dielectric, so it's possible that they it, rather than a pure metal.

      Pure tantalum on the other hand, is a great conductor.

    • Re:Metal dielectric!? (Score:3, Informative)

      by Cougar1 ( 256626 )
      The dielectric layer mentioned in some studies is Hafnium dioxide (HfO2). This is an insulator, not a conductor. HfO2, is good because it is a high-k material and it is thermodynamically stable in contact with Si.

      One reason for replacing polysilicon with a metal is that the HfO2 layer is not compatible with the polysilicon deposition process. Defects form in the HfO2 layer during the polysilicon deposition step. Another reason for replacing poly with a metal is to avoid poly depletion effects. Essentia

    • Re:Metal dielectric!? (Score:5, Informative)

      by inl101 ( 35878 ) on Wednesday November 05, 2003 @10:30AM (#7396508)
      I'm about 6 months away from my PhD in semiconductor physics.

      They mean metal oxides. Leading candidates are Halfnia and Zirconia. These are "High-K dielectrics".

      Using both reduces the Effective Oxide Thickness (EOT) of the gate dielectric. For the same thickness material, high-k dielectrics look like a thinner amount of silicon dioxide. Metal gates eliminate depletion effects in the gate (poly-depletion), which also makes the oxide look thinner.

      With lower EOT, the gate has better control of the channel, so leakage goes down.
    • The important thing to take into account is that a transistor is essentially a non-mechanical switch. Anything that can achieve the same result, semiconducting or not, could be used. At the same time when we are at the scales that are involved in a microchip then it is also important to have molecules that will not react with molecules making up other aspects of the chip.

      Like many subjects, if you are basing your knowledge on what you find in main stream text books then you are going to be missing a lot. T
    • I mightn't be able to help you out, but I think that Britney Spears [britneyspears.ac] knows a thing or two.
    • The issue with both copper and Hi-/Lo-K dielectrics is that they are chemically incompatible with silicon and many other tradional materials, that is, if they are allowed direct physical contact, either the silicon or the dielectric is irreparably damaged. For example Si sucks up Cu like a sponge and ceases to be a semiconductor in the process.

      For this reason you add barrier metals between Cu & Si, or barrier dielectric jackets between Cu and Hi-/Lo-K, or Poly-Si and Hi-/Lo-K. These are often are we

  • Time for change... (Score:5, Funny)

    by stm2 ( 141831 ) <(moc.selatigidseneg) (ta) (issabs)> on Wednesday November 05, 2003 @09:55AM (#7396186) Homepage Journal
    to MetalValley!

    Now, instead of "experiment in silico", it would be "in metal" (??) or "in Fe|Au|Cu" :)
    • Wouldn't work. A place called MetalValley would attract a bunch of washed up drunk metalheads looking for shows, and it'd be like high school all over again for the poor geeks.

      On the other hand. I'd definitely go there to see shows. :-)

  • What about... (Score:5, Interesting)

    by the_bahua ( 411625 ) on Wednesday November 05, 2003 @09:57AM (#7396196) Homepage Journal
    ...diamonds?

    I thought that the manufacture of diamonds was set, and only needed to step up its production. Gemesis [gemesis.com] has been making, for less than $100, gems that would be worth hundreds of thousands if naturally mined.

    The most promising thing about these diamonds is that, being cheap, they open the door for cpu cooling. Diamonds are tolerant of exponentially higher temperatures than silicon, so why aren't we hearing about intel, amd, motorola, ibm, TI, and sgi taking advantage of this new technology.

    Metal? What about metal is unprecedented? What about it has kept us from using it before? Diamonds are the future, not metal.

    • Re:What about... (Score:4, Insightful)

      by October_30th ( 531777 ) on Wednesday November 05, 2003 @10:09AM (#7396318) Homepage Journal
      Intense lobbying, FUD and outright threats from the diamond industry have managed to suppress any large scale production of perfect diamonds (you can't do chips using crude industrial grade diamonds).

      You see, diamonds are seriously overpriced luxury items. Although it is possible to manufacture cheap diamonds that are indistinguishable from the natural ones, it has never been done. Why? It would ruin the entire business model of De Beers & co. which is based on artificial scarcity. That's why they'd fight such projects to the bitter end.

      • Re:What about... (Score:2, Informative)

        by tyroney ( 645227 )
        Did you miss that whole bit [wired.com] about how there are at least two people that are making rocks that are only distinguishable from "real" diamonds because they are better?

        Just checking, because it souded like these people were hoping to do just what you mentioned as being heavily fought. And so far, they haven't been killed as far as I know.

        I, for one, welcome the death of our diamond-scarcity-based overlords.

        • And so far, they haven't been killed as far as I know.

          Yet. Even if they aren't physically killed, the cost of defending all the various lawsuits and/or lobbying for legislation by De Beers may just kill the companies.

        • I just love military people. You get the most flavorful language out of them, as well as amusement:

          So, for now, Clarke is sticking with cultured. But in the end, he insists, it won't really matter. "If you give a woman a choice between a 2-carat stone and a 1-carat stone and everything else is the same, including the price, what's she gonna choose?" he demands. "Does she care if it's synthetic or not? Is anybody at a party going to walk up to her and ask, 'Is that synthetic?' There's no way in hell. So I

      • Re:What about... (Score:5, Informative)

        by l3prador ( 700532 ) <wkankla@gmaTOKYOil.com minus city> on Wednesday November 05, 2003 @10:28AM (#7396483) Homepage
        Actually, it's currently being done [wired.com] by Apollo Diamonds [apollodiamond.com] and Gemesis, which was mentioned above. De Beers is fighting them as hard as they can, but even if they convince the public that manmade diamonds aren't worth anything as jewelry, they will still be able to use them for computing. However, production is not quite ready for large-scale chip manufacturing, which is why Intel and others have not yet turned to diamonds.

    • Re:What about... (Score:2, Informative)

      by mentaldrano ( 674767 )
      Diamonds? Until the diamond fabrication process becomes much more advanced, diamonds are a waste of time. Impurities are the culprit here. Many impurities = low mobility electrons = crappy chips.

      Electrical grade silicon (EGS) has a long purification process that it must go through to be of sufficient quality to make chips from. To give an example, there are roughly Avogadro's number of silicon atoms in one cubic centimeter of silicon (5.5x10^22 atoms / cc). After being purified, the MAXIMUM impurity

    • The Apollo Method [wired.com] (Skip to the end of the article)
      1. Place diamond wafers on pedestal. Depressurize chamber to one-tenth of an atmosphere.
      2. Inject hydrogen, natural gas (CH4) into chamber. Heat with microwave beam. At 1,800 degrees Fahrenheit, electrons separate from nuclei, forming plasma.
      3. Let it rain. Freed carbon precipitates out of plasma cloud and is deposited on wafer seeds.
      4. Let it grow. Wafer seeds gradually become diamond minibricks, building up at half a millimeter a day.
      5. Open chamber and re
      • intel is talking about this new substance being used within 5 years, as opposed to 10-15.

        In the end, diamonds may be great, but if they remain more expensive than silicon or metal-oxide, they aren't necessarily the best choice.

        nevertheless, when they do hit (and i personally believe they will) intel will certainly buy into the field.

        After all, they're more a development shop than a pure research shop. They almost certainly won't be the first to use diamonds in chips, but you can bet they'll be one of th
    • I'm curious, if artificial diamonds are now available to the public, cheap, and indistibguishable from the real thing...

      What's to stop me from buying a bunch, setting them, and selling them to jewellers who deal in used and reaping one hell of a profit?
      • By "indistinguishable" they generally mean to someone looking at a ring on a finger, or even under a light microscope. But there are ways to distinguish them in the laboratory, through fluorescence, and so forth. The impurities in natural diamonds are different from the ones in synthetics, so deBeers and dealers will still be able to laser-mark their diamonds as natural, and be able to distinguish forgeries, at least for the time being.

        The tough part is convincing brides-to-be to accept only the deBeers ma
        • But hey, the point is to make the groom cough up as much as he can afford, or more, right?

          Exactly, which is why I added "doesn't expect a ring" to my dating criteria.

          Limits my choices severely, but it's amazing how much less shallow people are when they don't equate money == love. I'm certainly happier, and the extra dough is fun for a nice trip for 2 somewhere private :)

  • Clueless, thy name is reporter (Score:5, Informative)

    by overshoot ( 39700 ) on Wednesday November 05, 2003 @10:04AM (#7396269)
    To clarify: the idea is to use a gate dielectric which has a higher dielectric constant than silicon dioxide. Most of the candidates are metallic oxides, nitrides, etc. That allows the transistors to have thicker gates for the same gate capacitance (which is how MOS transistors work).

    The chemistry of the non-silica gate dielectric requires that the gate itself be non-silicon, and metals are better conductors anyway. (For larger transistors, we're already running into trouble from the distributed resistance of the gates.)

    Hope that helps.

  • Seems like a lot of work when the could just license Long Run 2 [transmeta.com] technology from Transmeta. [transmeta.com]

    • Re:Long Run 2 (Score:2, Funny)

      by gorilla ( 36491 )
      Obviously the idea is to make Intel's own implementation, so they can then go and sue Transmeta for infringing Intel's patents.
      • If only that was funny and not a possibility... The implementations do seem to be quite different one is software controlled and available today (LongRun2) and the other is material based and will be available at some time in the future...
    • Via and transmeta and to a much lesser extent centrino and the G4 have all showed that a better processor LOGICAL architecture can achieve a better power/gflop ratio than conventional x86 chips. Of course they aren't pushing the speed limits for a single processor like the fast intels and poser pc chips do.

      but the point is that ratio is actually quite large. via's 7 watt chip is 2 to 3 times slower than intels 300 watt chips. which is about an order of magnitude. Moreover the transmeta designs have s

  • Isn't this old news? (Score:4, Funny)

    by wazzzup ( 172351 ) <astromac@nOsPaM.fastmail.fm> on Wednesday November 05, 2003 @10:04AM (#7396274)
    I thought it was already established that silicon implants were prone to leakage.

    But switching to metal? Man, I'd hate to walk outside on a cold Montana morning in February with those.

    What's that? Silicone? They're not the same? Never mind. Carry on. Sorry.

    So you're telling me SOI is NOT a busty gal in an angora sweater?

  • Hadn't IBM already done this (Score:5, Interesting)

    by adzoox ( 615327 ) * on Wednesday November 05, 2003 @10:10AM (#7396323) Journal
    I was aware that IBM's copper on silicon insulator already acheived less leakage and less power consumption, also increasing power (per Mhz) in each cycle. G3's (for Apple Computers have had this for over 2 years) and G5's also have it.

    Interesting how IBM has discovered that moving to metal for processors and away from metal for hard drives. (Newest Hitachi/IBM notebook drives use Pixie dust which is actually glass. The platters in these hard drives are also ferro impregnated glass platters)

    • you are thinking of SOI (silicon on insulator) which allows for less DRAIN current leakage to the substrate. this of course has nothing to due with the copper interconnects in the BEOL.

      all existing technologies in production (AFAIK) use poly gates as it survives the anneal and etching steps which copper and aluminum could never do in current configurations

      • Re:Hadn't IBM already done this (Score:4, Interesting)

        by adzoox ( 615327 ) * on Wednesday November 05, 2003 @10:52AM (#7396743) Journal
        No, the SOI is something different - it IS used in the G5's but G3's (750fx & Gx) used copper interconnects as well. It was the way that IBM figured out how to make the G3 so effiecient. The 900Mhz G3 is probably the coolest/best performing/per Mhz of any processor released in the past 3 years.
        • The 900Mhz G3 is probably the coolest/best performing/per Mhz

          Except of course for the same chip (the 750FX) at, say, 600MHz, or less. The G3 is seriously bandwidth-starved in most configurations I've seen (it supports a 200MHz FSB, but I've never seen it used with more than 167); scaling down the clock-speed gives sub-linear decrease in performance, linear (well, close enough; moreso than for most non-arm chips) decrease in heat and power consumption.

          Don't get me wrong, the 750FX is, in my opinion, the n
          • AMD's Athlon 64 can change frequency and voltage on the fly to any of several levels. Even the desktop version has this feature.

            Intel has been using copper interconnects since Pentium III "Coppermine"; AMD since Athlon XP "Palomino". AMD is currently (AFAIK) the only company producing CPUs using a SOI process.

            • Check your facts! (Score:2, Informative)

              by Kommet ( 27381 )

              The code name Coppermine had NO relationship with the metal used inside the chip. It was still an Al-on-Si chip, just like Katmai. Tualatin (last P-III core) and Northwood (second P4 core) were the first x86 Cu-on-Si chips from Intel (targeting Mobile/Server and Mainstream markets, respectively).

              Additionally, AMD was making Cu-on-Si chips back at the Thunderbird (first "L2 cache on core" Athlon) debut. All cores that came from Fab 30 in Dresden were Cu-on-Si while all cores from Fab 25 in Autin were Al-

    • No, IBM has gone to copper interconnects, which have lower resistance than the current aluminum ones that everyone else uses. IBM's innovation was finding a way to keep the copper from sinking into the silicon and ruining the delicate transistors underneath.

      Intel is actually talking about replacing the gate dielectric (which is silicon dioxide currently, even at IBM) with a metal or metal oxide, which has a higher dielectric constant. Higher dielectric constants mean a more effective gate for the same

  • Isn't Silicon a metal?

    • Re:*Switching* to metal? (Score:4, Informative)

      by overshoot ( 39700 ) on Wednesday November 05, 2003 @10:29AM (#7396494)
      Isn't Silicon a metal?

      No. The bonds between silicon atoms are covalent. A metal (e.g. copper) has a "cloud" of electrons free to move around in the lattice. Silicon is a semiconductor, with the charges bound to the atoms except when there's enough energy (typically thermal) to kick them loose.

    • No, silicon is a semiconductor, which means that its valence and conduction bands are not overlapping (as in a metal) at room temperature. It's not an insulator because the bandgap (the electrical distance between the valence and conduction bands) is small (about 1.1 eV).

  • Gee, moving back to metal gate fabrication? (Score:4, Insightful)

    by dido ( 9125 ) <dido@NoSpAM.imperium.ph> on Wednesday November 05, 2003 @10:22AM (#7396431)

    My course in VLSI design was many, many years in the past, but what I do remember is that early integrated circuits used metal gates in the fabrication process. That process was later abandoned in favor of polysilicon because poly was much easier to work with at smaller feature sizes (I'm a bit foggy on this one). Gee, so now we're going back to metal gate processes, and we'll have real metal-oxide-semiconductor field effect transistors again?

    If this is becoming easier to do at deep submicron level, I suppose processes for making deep submicron feature-sized Gallium-Arsenide MESFET's also got easier? Now wouldn't we just love to have such GaAs chips on our desktops... (I do know I'm forgetting another difficulty in working with GaAs, anyone care to remind me why GaAs is not as common as silicon today?)

    • That process was later abandoned in favor of polysilicon because poly was much easier to work with at smaller feature sizes (I'm a bit foggy on this one).

      Silicon gates can be self-aligning. Once you've got gate oxide, deposit a layer of polysilicon and pattern it, then use the remaining poly as a mask for the gates while the rest of the oxide is removed.

      I do know I'm forgetting another difficulty in working with GaAs, anyone care to remind me why GaAs is not as common as silicon today?

      There are several.

    • And has been since the late 1970s!!

  • Switching to metal gates and high-k gate dielectrics also eliminates phonon scattering. Increasingly, the atoms inside transistors are vibrating. Incorporating high-k gate dielectrics alone does not solve the problem.

    "This slows down the mobility of electrons," David said. "The metal gate seems to act like a sink for this phenomenon."

    David, however, declined to identify what metals Intel is experimenting with. AMD is working with nickel in its metal gates.

    So it's all a bit over my head, nickel cert [ndt-ed.org]

    • Nickel is the metal on top of the gate dielectric. Most of these processes actually have layers of material in each structure, though. For instance, the dielectric may have a layer of something compatible with silicon at the "bottom" and then something with high K above it, then something on top of that which gets along with the metal of the gate itself. Nickel is good because it's fairly nonreactive with the other materials in use.
    • Yes, metals (like Nickel) do conduct electricity, but most metal oxides do not! I suspect the mystery Intel metal and the AMD Nickel dielectrics are actually metal oxides. The benefit of metal oxides is that they have huge dielectric constants (which make better capacitative gates). I believe the world champion dielectric material is actually an oxide of Tantalum, but I cannot remember off the top of my head.

      As for the phonon question: in crystals the quantum of atomic motion is called a phonon. Elec

      • The nickel is probably a barrier layer to prevent chemical mixing of Cu or HiK with other materials in the device. Usually barrier layers are real thin, but are absolutely essential to prevent the device from morphing spontaneously into a glob of uselessness

        99% of all conduction in semiconductors is "phonon"-mediated/impeded. Metals conduct through a different mechanism. I doubt metal gates significantly affect semiconductor conduction through phonon modulation, especially since there is no direct cont

  • Some explanations and thoughts (Score:3, Funny)

    by fredrikj ( 629833 ) on Wednesday November 05, 2003 @10:31AM (#7396528) Homepage
    Would metal really be able to replace silicon? IANAEE, but...

    Wait, that only works on the law forums. Darn.

  • Heat=power (Score:3, Interesting)

    by nagora ( 177841 ) on Wednesday November 05, 2003 @10:35AM (#7396551)
    If the chip in your computer is as hot as a nuclear power station, should you not do what power stations do and hook it up to a steam turbine?

    One day, your computer may be the ONLY thing in your house connected to the outside mains supply!

    TWW

  • Does this mean I should start investing in liquid nitrogen suppliers? I hear pools develope leaks all the time. What will happen when the liquid nitrogen starts to drip? Note to self: don't store computer over anything valuable.
  • Right now, most chips have the aluminum (interconnect) to Silicon (gate) interconnect, but if the gate was metal, couldn't you replace the need to put down these two materials with a single metal deposition? I am not intimately familiar with the different steps of chip manufacturing, but even if the metal used for the gate was somewhat unusual (ie nickle), wouldn't it make sense to work towards eliminating one of these steps to reduce the overall manufacturing cost?

    myke
    • I am not intimately familiar with the different steps of chip manufacturing, but even if the metal used for the gate was somewhat unusual (ie nickle), wouldn't it make sense to work towards eliminating one of these steps to reduce the overall manufacturing cost?

      No.

      What the article was speaking of was using a metal as insulator. Since this doesn't make any sense at all, what they probably meant is a metal-oxide. You don't want an insulator as interconnect, because it doesn't interconnect.

  • The reason people use polysilicon for the gate now is so they can create the gate before they they do source and drain implants. This way the device is self-aligned, since the gate is part of the source-drain mask, producing a device with right amount of gate and source/drain overlap. When they created the source/drain regions using diffusion, it required high temperature, which melts metal. Now, with ion implanting, they probably can avoid high temperature steps after the metal gate creation to avoid melti
  • Even today you see several instruction-set architectures implementing single-instruction stream multiple-data stream (SIMD) integer and floating-point operations for multimedia applications, but we need to take this a few steps further--using a general-purpose processor with several special-purpose hardware units that are optimized and integrated for specific tasks, as shown in figure 11. [...] These special-purpose hardware units will provide orders of magnitude of equivalent general-purpose performance.
    • Ah, they've discovered the Amiga.
      And pretty much every main-, mini- and real micro- computer design. I guess the computer industry is finally catching up to the 70s fashion mini-revival of a few years ago.

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