http://www.sscs.org/MooreOnline/MooreTranscript.doc
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Gordon Moore 50th Anniverary talk.
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I actually think we're breaking the laws of Physics in some of this. We're printing 50 nm
lines with 193 nm light. We're printing lines at a quarter of a wavelength of the light.
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For those of you who haven't been to a lab recently this is a sort of cutaway picture of
what a modern step-n-scan production tool looks like. It's a several million-dollar tool
using an eximer laser and a variety of things
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. I remember doing a back of the envelope calculation about the time Intel was formed
back here and convincing myself that statistically if you went to layers that were less
than about a thousand angstroms, 100 nanometers thick, you'd probably get enough
fluctuations that things wouldn't be very good. But I didn't realize, I should have I
guess, the force was with us. Chemical forces really help. And you don't get a
statistical layer of atoms coming down when you oxidize the silicon, you get nice chemical
reactions that really do maintain the integrity of the layer down to the very, very narrow
layers. Here we are a couple of nanometers thick physically, electrically they look a few
nanometers thicker than that because I guess the electrons can't get all the way to where
we see the edges. And if you look with a transmission electron microscope that silicon
substrate, the insulator layer and poly crystal and the silicon on top, you see these
structures really are getting down to a few molecular layers thick. Well, you can't go
much further than that, but you don't have to in this case.
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Now, we get some problems coming along here. One of them that I think is an important
feature of this conference, and that is what is happening to the power? And here I'm
looking at 2 contributors to the power. The active power of the processors which are
getting up to power dissipations of a fairly bright light bulb and power densities the we
use to strive to get in power transistors. This is getting to be a problem. I don't want
a kilowatt in my laptop. It would be very uncomfortable. So from practical reasons the
power is going to have to roll off there.
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SLIDE 23:
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I suppose we can call this an exponential also, its kind of a step wise exponential. We
use to live with 12 volts and we went to 5 volts. We were going to stay at 3 for awhile.
But we discovered that cutting the voltage was so nice for power, that we just kept right
on cutting the voltage. Now every processor seems to pick an optimum voltage and we
continue to lower this principally to get the lower power, but of course, if we have much
thinner dielectrics, they like lower voltage also. Now, again, this can't go on forever.
You need at least a few hundred mili-volts, I don't know exactly what, just to overcome
some of the noise problems that will exist in digital devices. I suspect something around
1 volt is going to be a limit, but I sure have been wrong on a lot of these other things
that I suspected were going to have limits, and you folks probably know that a lot better
than I do. We chemists don't understand this kind of stuff so well. Especially that we
don't look at it closely anymore.
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SLIDE 24:
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But there are new things we can add that help with a lot of these problems. For example,
moving from silicon to sillicide gates helps considerably. We can continue to improve the
performance of the transistor by purposely straining the silicon in the region. You
strain it one way for the n channel device and the other way for the p channel device and
improve the performance of both transistors. As we look a little further down the road we
see things like a high dielectric constant, gate dielectric, which gives us the higher
electric fields while still keeping the leakage current down. And new transistor
structures.
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SLIDE 25:
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One of which is the tri gate structure I show in here. This is an interesting device
because it kind of changes at least the way I've always thought that transistors around
completely. And we got to make very, very narrow line webs down here in the 100 nanometer
or less, range. All of a sudden it doesn't make sense to deal with thin cells in the
other direction anymore. We just make a relatively thick film and make the transistor
move in the other direction. Here the gate wraps completely around the silicon, which is
sitting on a silicon insulator in this case. So you get a source, and a drain, and a gate
that depletes the silicon from 3 sides. You can make a fully depleted transistor in this
manner and cut the leakage current dramatically and get very high performance. It's the
kind of thing that you don't think about till you get down to the dimensions where it
suddenly becomes possible to build this kind of structure. This kind of a transistor
might carry us significantly further than we can go with only the techniques we thought
available in the past.
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SLIDE 26:
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Of course we have to be able to print finer and finer lines. To do that we need shorter
wave lights, we can't continue to print at a smaller and smaller fraction of the light
we're using. But the technology generation that we're seeing now, even by the regular
scaling we've been doing where we've reduced the line width by a factor of about .7 with
every technology node we go through, from today's volume production we can make
conventional transistors down to the 30 nanometer range. It takes 2 or 3 years between
generations. 3 years is the typical roadmap numbers the SIA puts out, the Semiconductor
Industry Association. Two years seems to be what we've been doing over that last few
years and expect to be doing for the next few generations. So, we're taking 10 plus or
minus 2 years of conventional scaling. Below 20 nanometers it's not clear with the
conventional devices will work, but something like that thin transistor I showed on the
last slide looks like a very realistic possibility. To make these very narrow lines, we
need a step in lithography.
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SLIDE 27:
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And this is the tough transition that we're going to have to go through, but we've been
working on a technology using what is called an extreme ultra violet (EUV). This is a
wavelength range that used to be called soft X-rays but X-rays are kind of a bad name in
the industry so the name was changed. But with the experimental system that
currently exists, we can print 50 nanometer lines and spaces, small dots and continue to
be improved. It gets to be much more complicated optically. There are no materials that
are transparent really in these ranges so you can't use lenses. You can't use masks to
put the radiation through; everything has to become reflective optics. Even air is an
important absorber, so you have to work in a vacuum. Simple mirrors don't work and so we
go with metallic mirrors. The mirrors we used here were something like 88 layers with
alternative new materials that give you the high reflectivity activity that we need. So
working with about 13-nanometer light that's something less than a tenth of the 193
nanometers that's used in production now. And the industry has been investing in this
kind of a system for quite a while.
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SLIDE 28:
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This is the proto type that exists in Sandia in Livermore. An industry consortium has
been working with Sandia and with the Livermore National Laboratory to develop this useful
technology. We're working with them because they use the technology that generally came
out of the old Star Wars program. And it seemed most productive to continue with the
group that had been working with the technology rather than starting all over someplace
else. But as you see, this is a pretty complicated looking machine and its every bit as
complicated as it looks. The mirrors have to be figured significantly better than the
Hubble telescope and then we have to be able to make them on a production basis, so it's a
real challenge.
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SLIDE 29:
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But one thing it will do, it will keep us on the exponential of the cost of the
lithography tool. (Audience laughter). Well as you see a lot of things are changing
exponentially. There's reason to believe that each of these has a problem. But I
remember thinking a million dollar machine was going to be prohibitively expensive for the
industry. Though we've blown though 10 million dollars for a lithography machine and
looking at things that are significantly beyond that. The feature is the productivity of
the tools has increased at the same time that the cost has again allowing us to decrease
the cost of the transistor to make cheaper and cheaper electronics.
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