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Extreme ultraviolet lithography : Pushing microchips down to the nanoscale

A WojdylaCenter for X-Ray Optics - LBNL

December 12th, 2013

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There’s plenty room at the bottom• I don't know how to do this on a small scale in a practical

way, but I do know that computing machines are very large; they fill rooms. Why can't we make them very small, make them of little wires, little elements – and by little, I mean little. For instance, the wires should be 10 or 100 atoms in diameter, and the circuits should be a few thousand angstroms across. – Richard Feynman (1959)

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Transistors• They are electron taps !

• Relays & vacuum tubes (“analog”)

• Solid state transistors (“digital”)

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What is lithography ?• (Photo) lithography– “To write in stone”• lithos (λίθος) “stone”• graphein (γράφειν) “to write”

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How do you make microchips ? (1/2)

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Mac

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Inverted microscope

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How do you make microchips ? (2/2)

source : Intel

Intel Core

x 30

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ce :

Mac

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How do we make them ?• We don’t actually make microchips,

but we provide the tools to make them

For, in order to work iron, a hammer is needed,and the hammer cannot be forthcoming unless it has been made; but, in order to make it, there was need of another hammer and other tools, and so on to infinity – Spinoza

A crane, as seen from the CXRO coffee room

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Source : ASML

Moore’s law“Where a calculator on the ENIAC is equipped with 18,000 vacuum tubes and weighs 30 tons,

computers in the future may have only 1,000 vacuum tubes and perhaps weigh 1.5 tons.” - Popular Mechanics (1949)

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Resolution is limited by the wavelength• Resolution is limited by the wavelength

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Why would you use Extreme UV ?• Current wavelength : 193 nm (excimer)– Go very low in resolution– Use of multi-patterning : • lots of masks : lower yield,

higher costs

• New wavelength : 13 nm– 15x smaller wavelength– Materials are available

xkcd

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Challenges for EUV Lithography• Source– Cyclotrons, FEL, Z-Pinch,

Laser-Produced Plasma– Works in vacuum

• Optics– Only in reflection– Coating (thin film)

• Materials– Appropriate polymers

source : Cymer

source : ALS

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A sense of scale (1/2)• 8 nm feature size– Compare it to the size of a red blood cell : 8 μm– Compare to the width of a DNA strand : 2.3 nm– Compare it to the size of an atom (12C) : 0.2 nm (VdW)

source : CXRO

EUV Lithography - All Talk Considered 1310 μm

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A sense of scale (2/2)• 0.1 nm precision (~λ/100)

over the size of a mirror• 1mm precision

over the size of Pacific ocean“Oh man, it’s raining !”

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Every perturbation is the enemy• Pollutants– Vacuum compatibility – Clean room (dust)

• Vibrations– “calm environments” already shake 1000x too much !

• Heat• Aluminum’s CTE: 22 μm/m/K

->Metrology is the key“If you can measure it, you can make it.”

Photon-noise limited experiments (CN Anderson, CXRO)

Effects of the dielectric permittivity of air vs. vacuum(A Wojdyla, CXRO)

Influence of temperature on the measurements (A Wojdyla, CXRO)

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Getting indust-real• First industrial tools shipped– 18nm resolution

ASML NXE:330 Demo tool

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Berkeley-Sematech MET 0.5NA• To renew the current Micro Exposure Tool (MET)• 0.5 Numerical Aperture

-> 8 nm resolution

Sematech members :ASML, IBM, Intel, Texas Instruments,…

Berkeley Sematech MET 0.5NA

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Designing, simulating, prototyping, tolerancing

wafer leveling systemwavefront sensing optical prototype

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Conclusions• Next step in semi-conductor industry

is EUV lithography• It’s not easy, because we have to overcome

Nature’s fundamental limits (so do you!)and environmental factors

• We’ve reached the bottom

• What’s next in tech ?– 3D chips, graphene transistors, spintronics, quantum computers…

xkcd

more at cxro.lbl.gov/METcontact : awojdyla@lbl.gov

Thank you for your attention

Drawing from Nobel prizes