All language subtitles for [MiUHjLxm3V0].en

- This is a microchip.

When you zoom in, you find
a nanoscopic computing city,

skyscrapers hundreds of layers tall

with hundreds of kilometers of
wires connecting everything.

And at the very bottom is this,

transistors,

billions of them.

They are the ones and
zeros of our computer.

The chip works by whizzing electrons

from transistor to transistor,

and the smaller you can
make those transistors,

the less the signals have to travel,

so the faster they can compute.

Plus, you can fit more
transistors into the same area,

resulting in a much more powerful chip.

So for over 50 years, transistors
got smaller and smaller,

and the number you could
fit on a chip doubled

every two years.

This became known as Moore's Law,

named for Intel's
co-founder, Gordon Moore,

after he noticed the pattern back in 1965,

and it's been one of the main
drivers of the tech industry.

But around 2015,

progress came to a screeching halt,

and we might have never gotten past it

if it wasn't for a single company
that makes these machines,

the machines that saved Moore's Law.

- Holy.

- This is a video about
the most complicated

commercial product humanity's ever built.

- That's insane.

- It costs a whopping $400 million,

and it is so bizarre that I
want to introduce it to you

with a thought experiment.

Imagine you are shrunk down

to the size of an ant,

and you are given a laser
that's strong enough to melt

through metal like butter.

Next, a tiny droplet of molten tin,

roughly the size of a white blood cell,

is shot out in front of you

around 250 kilometers per hour.

And your task is to hit
this not once, not twice,

but three times in a
row in 20 microseconds

with your little laser.

Well, that is exactly
what this machine does.

It hits one tiny tin droplet
three times in a row,

heating each one up to
over 220,000 Kelvin.

That's roughly 40 times hotter
than the surface of the Sun.

And it doesn't just hit one droplet,

it hits 50,000 droplets
every single second.

How often do you miss a laser shot?

- We don't miss them.

- What?

You do 150,000 laser shots a second,

and you don't miss one?

- Exactly.

- The same machine also contains mirrors

that might just be the smoothest
objects in the universe.

If you scale one up to
the size of the Earth,

then the largest bump would be

no thicker than a playing card.

On top of that, it is able to overlay

one layer of a chip
perfectly on top of another

and never be off by more than five atoms.

And this is all happening

while parts of the machine whip around

at accelerations of over 20 Gs.

(machine rattles).

For 30 years, almost everyone thought

that actually building this
machine was impossible,

and yet it exists.

There is only one company in
the world that can make it.

So what is this company and what is

this impossible machine they've built?

This video is sponsored by Brilliant.

More about them at the end of the show.

Now, just as a quick aside,

the makers of this machine
didn't actually sponsor

this video.

We just thought that the science
and engineering here were

so cool that we had to
make a video about it.

So let's jump straight in.

(upbeat music)

- [Derek] To make a microchip, you start

by taking silicon dioxide,
usually from sand,

and purifying it into ultrapure,

nearly 100% silicon chunks,

which is then melted down
in a special furnace.

Next, you lower a small
seed crystal into the vat.

Silicon atoms attach to the crystal,

extending its structure.

Then you slowly raise the
seed crystal while rotating it

and this results in a large,
single crystal silicon ingot.

- This is where the seed crystal would be.

Yeah.
- And then you pull it out.

- [Casper] Can I touch it?

- Yeah, you can.

- It seems like you
would not be able to hold

this from here.
- Yes.

- It even feels fragile.

Like if you kinda.

- [Person Off-Camera] Don't snap it.

- Yeah, I'm scared to break it.

- Yes.

- He's using more force.

- [Derek] The ingot is
then cut into wafers

with diamond wire saws,
up to 5,000 of them,

after which each wafer
is carefully polished.

Next, it's coated with a light
sensitive material called

photoresist.

There are different kinds,

but in a positive photoresist,

the areas exposed to light
become weaker and more soluble.

So if you shine light
through a patterned mask,

you can selectively weaken
parts of that coating.

Then, you rinse the wafer
with a basic solution

to wash away the exposed photoresist,

leaving the design imprinted.

So now you can actually turn this pattern

into physical structures.

This is often done by etching

into the uncovered silicon

by using either chemicals or plasma.

And then you deposit a metal, like copper,

to fill in those etched lines.

As a last step, you wash away
the remaining photoresist,

and now you've made a
single layer of the chip.

We've simplified this cycle
down to the main steps,

coat, expose, etch and deposit.

It repeats for every single chip layer,

and depending on the chip,

there could be anywhere
from 10 to 100 layers.

The bottom layer is the transistors.

This is the most complicated layer,

requiring hundreds of steps

that all need to be perfect.

The higher layers are a little easier.

These are the metal wires
that carry signals and power.

By the end, the completed wafer
can have hundreds of chips,

which are then cut into separate pieces,

packaged and put into products.

But by far the hardest
and most crucial step

in the process is where you
shine light through the mask

and onto the wafer.

This is photolithography,

and that's because this step determines

how small you can make the features.

- At first, it seems simple,

light passes through the openings

and it gets blocked by all the rest.

But as you try to print
smaller and smaller features,

the gaps in the mask start to approach

the wavelength of the light,

and that causes problems.

- And we can actually show it

because I happen to
have a, this is a mask.

This is a reticle.

- [Casper] A reticle or a mask carries

the design of one chip layer.

This reticle is filled with
microscopic lines and gaps,

around 670 nanometers across.

- And if I take like a laser pointer,

so this is a red laser.
- Yep.

- If I shine it through
it, then you see this here.

- [Casper] The laser has a wavelength

of around 650 nanometers.

When light hits the reticle,

its wavefronts bend as
they pass through each gap.

So, each gap sends out waves
that spread out and overlap.

Now, let's just look at the
light from these two gaps.

When the peaks of one wave line up

with the troughs of the other,

we say that the two waves are out of phase

and they cancel each other out,

so you get dark spots,

and when the peaks line up with the peaks,

the two waves are in phase.

They add up and you get bright spots.

- You can get interference.
- Yeah.

- Right, and you get
a diffraction pattern.

- Now, diffraction is inevitable.

So instead of fighting it,

designers actually use it to
get the patterns they want.

They kind of work backwards
from the eventual pattern

they want on the wafer,

and they design the slits

so that diffraction will occur

in such a way that it creates
the pattern that they want.

- You see three dots, the middle dot,

that's the original one.

That's the zero order.

And then on the left and the right,

you can see the first and the minus first.

Now, in order for us to have

this image resolved on the wafer,

you need to capture the zero and the first

and the minus first order.

- [Derek] The smaller
you make the features,

the larger this angle, alpha,

between the zero and first orders becomes,

so the larger your lens needs
to be to capture the light.

The size of the lens is described
by the numerical aperture

or NA for short,

which is just the sin of this angle.

So the larger that is,

the smaller the features you can print.

But there is a hard limit

to how large your lens system can be

when this angle is 90 degrees

and your numerical aperture is one,

where your lens would have to be infinite.

Fortunately, there is one
other thing we can change.

- This is a red laser.
- [Casper] Yeah.

- And a red laser has a
wavelength of 650 nanometers,

ish, I would say.
- [Casper] Yeah.

- And if I take a green laser

and this one has a wavelength of 532,

then you can see that the green dots are

closer spaced than the red dots.

- [Derek] That's because the light

from the two different
gaps doesn't have to travel

as far to match up in phase again.

So, the orders end up closer together.

So with a smaller wavelength,

you can print smaller
patterns using the same lens.

All of this is captured
by the Rayleigh Equation,

which determines the smallest feature size

or critical dimension.

- But since there's a limit

to how much you can increase
the numerical aperture,

I mean to one,

over time, the only way to keep making

smaller and smaller features is

by using shorter and shorter wavelengths.

So this is exactly what happened

up until the late 1990s,

when the industry settled on 193 nanometer

deep UV light.

This was the light that was used to make

all of the most advanced chips

right until around 2015.

But by that point, scientists
had reached a limit

to how small they could make the features.

And Moore's Law was about
to run into a brick wall.

So a radical change was needed,

a change that had been
brewing for around 30 years.

All the way back in the 1980s,

Japanese scientist, Hiroo Kinoshita,

came up with a crazy idea.

Why not use much shorter wavelengths,

like x-rays of around 10 nanometers?

In theory, that should allow you to print

much smaller features,

but you quickly run into a problem.

X-rays at these wavelengths have

enough energy to eject
electrons from their atoms,

so most materials absorb them.

But unlike medical X-rays which have

wavelengths shorter than one nanometer,

these are still long enough
to interact with air.

So, air absorbs them too.

That meant that Kinoshita's
setup had to be in a vacuum,

but even worse,

he couldn't use lenses to focus the light

because the lenses would absorb it too.

So, it seemed like this
idea would never work.

- [Derek] But around 1983,

Kinoshita stumbled on a paper

by Jim Underwood and Troy Barbee.

Their work focused on special mirrors

that could reflect x-rays

with a wavelength of 4.48 nanometers.

So, Kinoshita was intrigued.

Curved mirrors can focus
light just like lenses do.

If he could figure out how to make

these special mirrors for
the wavelength he was using,

then this could be another
way to do photolithography.

The mirrors work something like this.

When light crosses from
one medium to another,

say, from air to glass,

it bends or refracts.

Some of it goes through
and part reflects back.

How much gets reflected depends
on things like the angle,

the light's polarization,

and most importantly for us,

the difference between
the refractive indices

of the two media.

The larger that difference,
the more light is reflected.

And Underwood and Barbee
used that principle.

They made a super thin layer of tungsten,

less than one nanometer thick,

thin enough that x-rays could pass through

without immediately being absorbed.

When x-rays hit the layer
at a specific angle,

the tungsten reflected less than 1%.

Then, they carefully
tuned the layer thickness

so the path length of the
transmitted x-rays was

only one quarter of its wavelength.

Then they added another layer,
this time out of carbon.

It has a higher refractive
index than tungsten

for wavelengths of 4.48 nanometers.

The x-rays hit the boundary

and a little bit more reflects,

but this time the phase is inverted

or it's changed by half a wavelength.

This happens when any light moves

from a lower refractive
index to a higher one.

Now, by the time this new
reflected wave reaches

the tungsten boundary,

it has traveled another
quarter of its wavelength

for a half wavelength in total.

So the two phases line up

and the waves interfere constructively.

Underwood and Barbee kept doing this trick

for a total of 76 alternating layers,

so that in total they could reflect back

much more of the x-rays.

Now, they only managed to reflect

around 6% of the light,

but it was a proof of principle

that you could reflect x-rays.

- So Kinoshita saw the possibilities.

He got to work, and
after around two years,

his team designed and built

three tungsten-carbon
curved multi-layer mirrors

to reflect 11 nanometer light.

And with it, he managed to print

lines four microns or
4,000 nanometers thick,

proving that at least in theory,

x-ray lithography was possible.

A year later in 1986,

he went to present his findings

to the Japanese Society
of Applied Physics.

Proud and excited, he explained his setup

and showed his image.

But to his horror, the
audience refused to believe it.

- [Kinoshita] Unfortunately,
the audience was

highly skeptical of my talk.

- [Casper] Kinoshita was devastated.

He later said, "People
seemed unwilling to believe

that we had actually made
an image by bending x-rays,

and they tended to regard the whole thing

as a big fish story."

- Nobody believed that this
was a viable way forward,

and unfortunately, the reaction was

at least somewhat justified.

First, this light isn't naturally produced

by anything on Earth.

The closest natural source is the Sun.

- We had to basically build an
artificial sun here on Earth.

- [Derek] Most scientists,
including Kinoshita,

produced x-ray light using

a particle accelerator or a synchrotron.

- [Jos] It gives an
enormous amount of power.

It's as big as a soccer field.

You can fuel a whole fab.

The problem is if the light goes out,

the whole fab goes out.

- So each machine needed
its own power source.

But even if you could produce the light,

you'd need to make
incredibly smooth mirrors

to actually focus and
print those tiny features.

You would need the smoothest
objects in the universe.

- Okay, so I got a football

and I've got a bouncy ball
and a cobblestone street.

Now what do you think is
gonna happen when I drop them?

The football basically
bounces straight up,

but for the bouncy ball,

it just shoots off to the side.

And it's because the
surface is relatively flat

for the football, which is much larger,

but it's super rough for the bouncy ball.

And a similar thing happens with mirrors.

If the surface is super rough

compared to the size of the wavelength,

then the light scatters randomly.

Now it might look smooth,

but if you zoom into a mirror,

you find something that looks like this,

you find all these crazy bumps.

And now to measure the roughness,

what you do is you take
the average of these bumps

and that will give you your mean line.

Now, for a normal household mirror,

the average height is
about 4,000 silicon atoms.

But for Kinoshita's mirrors,

which not only needed
to reflect x-ray light,

which has 100 times shorter wavelength,

but also needed to minimize scattering,

you know, so that all the
photons make it onto the wafer,

it needed to be way more smooth.

It needed to be atomically smooth.

In fact, the average bump could only be

about 2.3 silicon atoms thick.

- If one mirror would
be the size of Germany,

the biggest bump would be
about a millimeter high.

- [Casper] But Kinoshita
refused to give up.

- [Kinoshita] However,
my belief did not change.

- [Casper] And soon help would
come from an unlikely place.

- Across the Pacific,

around 70 kilometers
east of San Francisco is

Lawrence Livermore National Lab,

a lab that was born out of the Cold War,

heavily funded by the US government,

and built for one purpose
and one purpose only,

nuclear weapons.

The lab was founded by the
inventor of the Cyclotron,

Ernest Lawrence,

and the father of the
hydrogen bomb, Edward Teller.

And over its lifetime, they designed

over 10 fusion-type nuclear warheads.

So part of their research focused

on what happens inside
nuclear fusion reactions.

Fusion reactions release
a lot of x-ray light,

light that they had never been
able to capture and analyze.

But now, using those
special multilayer mirrors,

there was a chance.

- [Casper] One of the scientists tasked

with making this work was Andrew Hawryluk.

And within a few years,

he and his team used
multilayer mirrors to reflect

some x-ray light.

But then in 1987,

Andy got a visit from a
professor from Cornell.

- He was very impressed
with the technologies

that we developed.

And he looked at me at the
end of the day and said,

"This is all very interesting
and very neat and stuff,"

but his words, and I'll remember
it to the day I died, was,

"Can you do anything
useful with this stuff?"

And this was the day before
a Christmas shutdown in 1987.

And I was so inflamed by that comment

that I went home and for the next 10 days,

I wrote up a multi-page white paper.

- [Casper] He applied these
mirrors to lithography,

to print chips using x-rays.

Around five months later,
Andy presented his findings

at a conference.

But like Kinoshita, it
was not the response

he was hoping for.

- It was extremely negative.

That was the low point in my career.

I was literally laughed off the stage.

And I kid you not, every
person who I looked up to

in the field,

they were listening to my talk

and they came up to the microphone

and told me basically
why it wouldn't work,

how stupid an idea it was.

Later that week, I flew back
and the following Monday,

my boss asked me, "How did it go?"

And I looked at him and I said,

"I will never speak of it again."

(uptempo music)

- [Casper] But then three days later,

he gets a phone call from
someone named Bill Brinkman

from Bell Labs.

- [Andy] And so I walked
over to my boss and I said,

"Just got this phone call from
a guy named Bill Brinkman.

Do you know who he is?"

And my boss's eyes popped open and said,

"Yeah, he's the Executive
Vice President of AT&T."

And I said, "Well, he just called me

and asked me to fly out to
New Jersey and give a talk."

The response from my boss said it all.

He basically said, "Well, you gotta go."

- [Casper] At Bell Labs,
Andy found fellow believers

and it couldn't have
come at a better time.

Over the past 30 years,

the US government had invested

billions of dollars into
national labs to maintain

the country's technological
edge during the Cold War.

But by the late 1980s,

the Cold War was slowing down

and all these labs were
sitting on research

that had commercial potential.

So the government encouraged
the labs to partner

with US companies

to turn that research into products

and to stimulate the economy.

And the government would
then supply seed money.

And so Bell Labs partnered
with Andy's labs and two others

to keep developing x-ray lithography.

And by 1993,

the first international conference
for x-ray lithography was

held in Japan, near Mount Fuji.

In the opening address, Kinoshita said

that, "As long as we
do not lose the desire

that has sprung from within us,

technology will steadily advance

from the micro to the nano to the pico."

They even gave the technology a new name,

extreme ultraviolet lithography,

or just EUV.

- But then in 1996,

the US government cut
funding for the project.

This spelled disaster for the
big chip companies like Intel.

The industry estimated

that the 193 nanometer
lithography tools would fall

behind Moore's Law by 2005,

but there were no other alternatives.

So Intel, Motorola, AMD and
other companies got together

and invested $250
million to keep it going,

making it the largest investment ever

by private industry

in a Department of
Energy research project.

By the year 2000, the
labs had produced this,

the Engineering Test Stand.

It was the first fully
functioning EUV prototype.

It produced 9.8 watts of
13.4 nanometer EUV light,

which was then reflected by eight mirrors

from the source to the mask to the wafer.

It could print 70 nanometer features

and it proved that EUV could work.

- It was a milestone to get

the Engineering Test Stand to work.

It demonstrated to people like Intel

that, you know, good
engineering will get us there.

- And then it seems like
you've got the prototype,

shouldn't be too hard to
then commercialize it.

- That's what they thought.

(Andy and Casper laugh)

- But the prototype had a major flaw.

It could only print
about 10 wafers per hour.

And to make EUV economically viable,

it would have to print
hundreds of wafers per hour,

24/7, 365 days a year.

The main reason output was so slow was

because the light reflected
off of eight mirrors

and the reticle,

which is also a mirror, just
with the design imprinted.

Traditional masks that
allow light to pass through

don't work because, well,
they absorb all the light.

Each mirror had a
reflectivity of around 70%,

which is close to the max,

but after nine bounces,

you are only left with 4% of the light,

which means that out of every 100 photons,

only four make it to the wafer.

So you might think just
use way fewer mirrors,

but that only works up to a point.

When you focus light
with any optical system,

you always get some distortion.

For example, rays that pass
through the outer edges

of most lenses focus
light slightly different

from those near the center.

This is called spherical aberration.

And normal cameras correct for this

and other aberrations by
using multiple lenses.

And a mirror system is no different.

- You need to have a
certain amount of mirrors

before you can say I have my
aberrations under control.

In reality, the systems
of today have six mirrors.

- That helps a little.

But after reflecting off
six mirrors and the reticle,

you are still only left with
around 8% of your light.

So they needed to drastically increase

the source power to at least 100 watts.

Now to most companies,

that tenfold increase seemed impossible.

Even people who worked on the
Engineering Test Stand noted

that while EUV technology
itself is a done deal,

there were six zillion
engineering challenges

to make it a fab-line reality.

And so one by one,

American companies walked away

from developing a full
EUV lithography machine.

That left just one company, ASML.

ASML, which used to stand for

Advanced Semiconductor
Materials Lithography,

is located in a small, nondescript
town in the Netherlands.

It spun off from Philips back in the '80s

with little more than a shed

and a barely working
wafer stepper to its name.

But Philips also gave them people,

Jos Benschop, ASML's first researcher,

and Martin van den Brink,

who would eventually become ASML's CTO,

and EUV's greatest champion.

- And he is really like the
Steve Jobs of lithography.

And he saw EUV coming.

- ASML had joined the US
EUV consortium earlier

and now it became their task to find a way

to commercialize EUV.

They would work together with
their German partner, Zeiss,

where Zeiss would take
care of the mirrors,

and ASML would focus on the light source.

One of the first decisions when making

any lithography system is
deciding which wavelength to use.

- In the early days, anything between

five and 14 nanometers was explored.

The thing is you need to find a source

and you need to find optics that reflect

the wavelengths.
- Right.

- So you have to look for the combination.

- Underwood and Barbee had already made

mirrors that could reflect
light of around four nanometers.

And since that wavelength is so small,

it seems like the obvious choice,

but the maximum reflectivity
for those mirrors was

only around 20%.

So after hitting six
mirrors and the reticle,

you are just left with
0.00128% of the light,

which is way too low.

Fortunately, further
researchers also looked

at two other pairs,

silicon and molybdenum,

which had a theoretical
maximum reflectivity of 70%

for wavelengths around 13 nanometers,

and molybdenum and beryllium

with a theoretical maximum
reflectivity of 80%

for wavelengths around 11 nanometers.

So the choice seemed obvious, right?

I mean, pick the shorter wavelength

and the higher reflectivity.

But it turns out that
beryllium is extremely toxic

and it's also difficult to handle.

So scientists focused on
silicon and molybdenum instead.

To make the mirrors, Zeiss used
a process called sputtering.

A target of coating material is

bombarded with either plasma or ions,

causing atoms to be ejected, fly off

and stick to the mirror.

This is a messy process,

so the layers end up
having bumps and gaps.

- There was a nice trick that actually

the team in the Netherlands
perfected with ion beam.

You just shake it a little bit

until the atoms falls in the
hole where it needs to be

and then it's all flat.

- [Casper] With the
mirror design locked in,

ASML needed a source for
that specific wavelength.

- So it was 13.x.
- Yeah.

- Okay, now the next good
question is what's the x?

Now you look for the source.

So there are basically
three ways to generate EUV,

to build a sun on Earth.

- [Casper] The first method
which early researchers used

was the Synchrotron,

but it was quickly ruled out

because each machine
needed its own source.

The other two methods are
based on the same principle.

When an electron recombines with an ion,

the ion drops to a lower energy level

and it releases that
excess energy as a photon.

And if you choose the ion just right,

then that photon will have
exactly the wavelength you need.

Now, there are two ways
you can create those ions.

The first is you take a metal,

heat it up until you get a metal vapor,

and then you apply a strong
electric field across it.

This causes free electrons
to knock into nearby atoms

and ionize them.

If you then turn off the electric field,

the electrons recombine with
the ions and produce light.

This is discharge-produced plasma.

- [Jos] That's the concept we use first.

- [Casper] Yeah.
- Because of its

relative simplicity.

And we quickly got it to a few watts.

We wanted to get 100 watts
and we struggled forever.

- So you couldn't scale it.

- We could not scale it.

- They needed a drastic change.

So they switched to the second method.

This method uses a high powered laser

to hit a target material,

creating a plasma

that's more than 220,000
degrees Celsius hot.

The electrons have so much energy

that the nucleus can't
hold onto them anymore,

and up to 14 electrons
escape their orbits.

After the laser shuts off,

the electrons and ions
recombine to produce light.

This is laser-produced plasma

and it was the only method
that seemed scalable.

In fact, this was the same method

that the Engineering Test Stand used,

a 1,700 watt laser fired
into a stream of xenon gas

to produce 13.4 nanometer light.

But xenon had a big problem.

The conversion efficiency that is

the ratio of usable light

to the amount of power
you put in was terrible.

It was only around 0.5%.

That's because while xenon does emit light

in the 13 to 14 nanometer range,

there's much more light
released around 11 nanometers.

So most of the energy
went into making light

that the mirrors couldn't reflect.

Plus, the laser didn't
ionize all the atoms.

So, leftover neutral xenon atoms would

strongly reabsorb some of
that 13.4 nanometer light.

So ASML started looking
at another material, tin.

Now, tin has a much higher emission peak,

around 13.5 nanometers,

which results in a five to 10 times higher

conversion efficiency than xenon.

But just like xenon, neutral
tin atoms also absorb

EUV light.

So they came up with a crazy idea,

to shoot one tiny tin droplet at a time.

But to get the required power,

you would have to make and hit

thousands of droplets every second,

all of which have to be the
exact same shape and size.

But it turns out that
you can't instantly make

thousands of tin droplets
that are the exact same.

So, they found a workaround.

To make the droplets,
extremely pure tin is melted

and pushed through a microscopic nozzle

by high pressure nitrogen.

This nozzle vibrates at a high frequency,

breaking the stream into tiny droplets.

These droplets are
irregular in size, shape,

velocity and distance,

and the whole process is chaotic.

- That's like our magic sauce,

is how do you modulate that tin jet

so that it forms the droplets we want

and that they're stable?

- I think we found some paper
that describe this process

and it was sort of eyeopening to me

that it seems like all the droplets

actually come out irregular
out of the nozzle,

but then before they reach the side

where they get hit by the laser,

like the little irregular
droplets come together

to form these perfectly spaced,

perfectly regular droplets

that are about the same size and shape

and all traveling at the same velocity.

That feels like magic to me, Jayson.

- Yeah, it's exactly that.

It's how do you take a
long stream of a tin jet

that wants to break up into
all these irregular droplets

and like force onto it

that it's gonna collapse
into a single droplet

and then happen again and again and again?

- [Casper] You also don't
have that many variables

to play with.

You've got the pressure

with which you push out the tin

and at the frequency of the nozzle.

Yeah, it seems like a
hard problem to solve.

- There's not a whole lot
of variables to play with.

And so mastering that
modulation of the jet is

how we make the droplets.

- [Casper] But these droplets
not only have to be identical,

they have to be moving incredibly fast.

- What will happen is if the next droplet

that's coming down the line is too close,

then it'll actually get like disturbed

and mess up the next plasma event.

So we have a requirement

which is both that we make
50,000 droplets per second,

but also that they're
traveling extremely fast.

- [Casper] By 2011, their
laser-produced plasma source

reached 11 watts,

which was more than
double what they managed

with their previous source.

But they were still limited
to just five wafers per hour.

So, they needed to increase
the power and fast,

because they promised they'd
hit 60 wafers per hour

by the end of 2011.

Unfortunately, this new
method had a major flaw.

- Now the problem with the tin
issue, you hit the droplet,

you generate EUV with a very
decent conversion efficiency.

Where does the tin go?

Because like, you know,
30 centimeters away,

you have this atomically flat,

very beautiful, very expensive mirror

from our friends at Zeiss.
- [Casper] Yeah.

- And in the early days,

we would coat a thing within.

(Jos clicks fingers)

Like this.
- These machines need

to run for a year.

You're putting liters of tin
through this plasma event

and a single nanometer of tin,

if it was to land on
that collector mirror,

you'd have to take the
collector outta commission.

We need to keep it almost
perfectly clean for a year.

- Yeah, how do you even approach that?

- So our main tool here is
the hydrogen gas, actually.

- [Casper] They fill the chamber

with low pressure hydrogen.

This slows and cools
the tin particles down.

And even if something
makes it to the collector,

the hydrogen pulls it off to
form a gas called stannane.

This way, the machine
cleans the collectors

while it's running,

but that hydrogen gas also gets hot

from all those tin explosions.

So they need to keep
flushing new, cooler hydrogen

into the system while
flushing out the stannane

and hotter gas.

But they have to get the
pressure and the flow rate

just right.

I mean, too little hydrogen

and the mirrors would get too dirty,

but too much hydrogen
would not only absorb

too much EUV light,

but it would also cause
the system to overheat.

- The question is how much heat is there?

How much energy is being
deposited into the gas?

And we were stumped for quite some time.

If you look at a EUV light source,

what you'll see is that
it's kinda like a globe

of like purple-ish red light

and you kinda ask yourself
like, why is that happening?

So we bought an ultra-fast camera.

What we realized is that
after every plasma event,

there's a shockwave that goes

propagating out into the hydrogen gas

and it's extremely repeatable.

And you think to yourself,

there must be like an
explanation for this.

And there's this formula,

the Taylor-von Neumann-Sedov
formula that explains

point source explosions in an environment,

in like, say, a nuclear
blast out to like supernova.

So I took this formula,

it like exactly describes the data.

It's just fantastic that we're seeing

these, like, tiny little
supernovas happening

in our vessel 50,000 times a second.

- And is that a fair
way to think about this,

like creating mini supernova?

- Yeah, it's actually pretty similar.

It's almost like very similar to a,

like a type 1A supernova, it turns out,

where you kind of have an object

that just fully evaporates
and explodes apart.

And when all that energy
goes into the hydrogen gas,

it produces a shock wave, a blast wave

that comes flying out,

which is basically the same thing.

If you look up in the night sky,

there are these like remnant supernovas

that you can see coming from space.

- [Casper] Using those
energy calculations,

they discovered they needed to flush

the hydrogen at incredibly high speeds,

around 360 kilometers per hour.

That's more than a Category 5 hurricane,

even if, you know, those
speeds are at low density.

But 2012 came and went

and they still didn't have enough power.

In fact, by 2013, ASML
just reached 50 watts

by shooting 50,000 tin
droplets per second.

But this increased power came at a price

because more power means more heat,

heat that ends up slightly
shifting the mirrors,

resulting in misaligned light
and misaligned chip layers.

So Zeiss built a nervous system

directly into the optics,

robot-guided sensors
that constantly measure

the exact position and
angle of each mirror

down to the nanometer at the pico-radian,

which is absolutely insane.

- So how accurate do we
need to control this mirror?

Now one of the things, you
can do a thought experiment.

- [Casper] Okay.
- And I can place

a little laser on the side of this mirror.

Then we go all the way to the Moon

and we put a dime here.

So then this light travels

all the way here and
then with the accuracy,

I can control this mirror.

- Yes.
- I can decide

whether I point to this side of the dime

or whether I point.
- That's insane.

- To this side of the dime.

- What, that's crazy.

- So you can see that
the pointing accuracy is

that's also in pico-radians.

That is something very extreme.

- This allowed them to control the light

even when the power increased.

While Zeiss was doing a
stellar job with the optics,

ASML was still struggling
with the power source.

The problem was that the
tin droplets were too dense,

meaning that most of the
emitted EUV light was

still getting reabsorbed

by the neutral atoms
before it could ever reach

the collector mirror.

- The way we blasted the droplet was

so not enough light, too much debris.

- To make matters worse,

they could see that
about 10 years from now,

they would need a new
generation of machine,

a high NA EUV machine,

essentially one with a larger optic system

that could print smaller features.

So what did they do?

They decided to double down and invest

in the next generation

before they even got
the current one to work.

- The most doubtful period
was in the beginning.

So I started to work on this in 2012.

By that time, EUV was not working

and there was this crazy idiot

working on the next generation

where we could not even make

the EUV light in the first place.

- Not only are you all in on EUV,

you're doubling down even before you know

if EUV is gonna work.
- Yes, yes.

- But to keep funding the development,

they needed money and lots of it.

So, they turned to the
very people who needed

this technology.

- ASML reached out to its main customers,

okay, you want this technology

for the next generation of chips?

Well, you need to make us able

to invest more by investing in us.

- Intel invested around $4.1 billion

and Samsung and TSMC invested
another 1.3 billion combined.

So they can keep the research going,

but with no product to show,

customers were running out of patience.

- We were crucified at every conference

that the promises we made last year,

we were unable to live up to.

- Yeah.
- And they said,

"This is what you showed two years ago.

This is what you showed last year

and this is what you're
telling me this year.

So why would I believe you?"

- They were getting desperate.

- But this was, I think,
about 2012 or '13,

we were struggling to get the EUV power up

and Kinoshita visited us.

I took him to dinner
in a small town nearby

and across from the
restaurant was a Maria Chapel.

And now, you know, science,

we have come to the limits of science.

Hey, let's go for Divine intervention.

So we went to the chapel,

so Kinoshita just to be
safe lit three candles

for the three suppliers that
were pursuing EUV technology

at the time.

And lo and behold, and I
have the data to prove it,

there is a very strong correlation

between us lighting the
candle and power going up.

It's not a causal effect, but
there is a strong correlation.

- The big idea was instead
of hitting the droplet once,

hit it twice.

- [Jos] One shot to hit the droplet

and it expands in like a pancake shape.

- [Casper] Yep.
- And then,

only then have the second shot,

the more powerful main pulse

where you evaporate the pancake

and turn it into a plasma.

- [Casper] Yeah.
- This was

a major breakthrough.

- [Casper] By changing the target

from a droplet to a pancake,

you got a larger surface area
for the laser to vaporize,

but without the cost of adding
more debris or neutral atoms

because now the tin is
vaporized all at once.

By 2014, they finally managed to hit

that coveted 100 watts mark.

But improvements in multi patterning

with 193 nanometers

now meant that EUV would only be useful

if the source reached at least 200 watts

and made 125 wafers per hour.

- The source went from 100 to 200,

but as the industry moved
on, nobody waits for you.

You know, they find other solutions.

We had to catch up.

So, it was a moving goalpost.

- One of the problems was
how do you perfectly time

the laser so you hit
each of these droplets?

- So the analogy is a bit like a golf ball

that you need to land in
the hole 200 meters away,

not like land on the green,

not bouncing and get in the hole,

but like land in the hole every time.

That's the level of precision that we need

to deliver the droplets.

Those droplets are traveling

through this like
maelstrom of hydrogen flow.

The speeds are tremendously high,

like shooting golf
balls through a tornado,

and then right when it lands at the hole,

that's when it needs to
get hit by the laser.

So in order to basically
track the droplets for that,

we use laser curtains and
we can sort of look at

when does the droplet pass
through a laser curtain.

Those scattered photons tell
us basically when and where is

the droplet,

and then importantly tells
us when to fire the laser.

So we actually have to take into account

how long will it take for
the light pulse to hit

the droplet after we send the pulse.

- Now by 2015,

they were getting closer and closer

to that coveted 200 watt mark,

when all of a sudden the ASML
board members got summoned.

- This was one of these decisive moments

where our customers were
really thin on patience

and Martin and all the board members were

summoned to Korea to show

200 watt and they were
really fed up with it.

You know, you either show
it now or you go away.

And when they entered the plane,

the experiment was still running.

- [Casper] Okay.
- When they exited

the plane,

they had the first result
demonstrating 200 watt.

This is how close we came.

- With the source power up,

there was one final problem
that had to be solved

before they could begin
manufacturing their machine.

See, while the hydrogen gas did protect

the collector mirror from debris,

it wasn't perfect.

All the intense, high energy photons

and hydrogen ions zipping around

deteriorated a very special
top coating on the collector.

So they still had to clean
the mirrors every 10 hours,

which, you know, is
terrible for productivity.

Martin van den Brink asked
for updates every day

on their progress.

But then one of the engineers noticed

that every time they
opened up the machine,

the mirrors suddenly seemed cleaner.

- That he kind of chimed in and said,

"Oh, wait a second.

Whenever we opened up the machine,

oxygen comes in and our problem is solved.

Couldn't we think of a way to add

just a little oxygen to our system

and make sure that the
collector stays clean longer?"

And so they started experimenting

with the amount of oxygen that was needed

in the vacuum and then
finally got to this point,

okay, if we add so much oxygen,

we'll keep the collector clean for longer.

- With this fix, ASML's machine could run

continuously for much
longer and it finally became

commercially viable.

By 2016, orders started pouring in

and now all of the most
advanced chips need

ASML's machine,

making them perhaps the most important

tech company in the world.

ASML's first commercial machines had

a numerical aperture of 0.33

and could print 13 nanometer lines.

These are called the low NA machines

and ASML still makes them.

But the machine that Jan's
team started working on

back in 2012 was the next generation,

which had a larger optic system

so they could print even smaller features.

This is the high NA machine

with a numerical aperture of 0.55,

and we get to see their
latest version up close.

- How much is the machine?

- We always say north
of 350 million euros.

- And you can actually buy it, right?

- You can if you want, yeah.

- If I had the money I could buy it?

- Yes, you could.

- How many people have seen this before?

- We really limit the amount of people

that get to go inside the clean room.

- [Casper] ASML's machines are built

in a super strict clean room.

In any cubic meter, there can
be no more than 10 particles,

only 0.1 microns large,

and nothing bigger than that.

A spec of pollen is around 20 microns

and extremely fine sand
is around 10 microns.

To put all of this in perspective,

hospital operating rooms,

which have to be extremely clean,

only allow a maximum of 10,000
particles per cubic meter

that are 0.1 microns wide.

It's so unfair how much
better Marc looks, though

in his light suit.

I feel like a little Smurf.

- Okay, so we're gonna go
through the air showers,

so you're gonna have to do as I do.

- [Casper] Okay.

So this is brushing down all the particles

that are still on us.

- [Marc] Yes, so this
is like super clean air

blowing us clean.

- [Casper] This place is huge.

- [Marc] It's huge.
- [Casper] It's insane.

I've been in a clean room
a couple times before,

but it's nothing compared to this.

Are there any secret areas here

where almost no one has access to?

- [Marc] I can't tell you.

(Casper laughs)

- [Casper] Great answer.

- [Marc] Okay, so this
is the total system.

- [Casper] This is crazy.

Look how big it is.

This is the most advanced
machine humanity's ever built.

It's taken many, many years,
decades of development,

many billions of dollars,

all to get this humongous beauty.

So this is the first high NA machine.

- [Marc] Yes.

So if you saw pictures on
the internet or whatever,

that's this machine.

So the very first lines ever
printed at eight nanometers

and stuff, that was this machine.

- [Casper] This smoothest object on earth.

- [Marc] Yeah, it's all in here, yeah.

- [Casper] Wait, so let me
see if I can figure this out.

This is the light source.

It's where they make
the extreme ultraviolet.

- [Marc] Yes.

- [Casper] And then the laser
must come in from there.

- [Marc] Yeah, let's
take a look at the laser.

- [Casper] In fact, we got to see

just how the laser and light source work.

I think we're entering
the laser system here.

Marc's just making sure I think

that we can actually film here,

that we're not catching
anything we're not supposed to.

Oh wow, this looks dangerous.

Now the laser system is covered

by all of these brown cabinets,

but here is a model version.

A carbon dioxide laser of
just a few watts enters

this amplifier where it bounces around

until it's roughly five
times its original power.

It then goes through a total
of four different amplifiers

to bring the final laser
up to 20,000 watts,

which is four times stronger
than lasers that cut

through steel.

- Over here we have the
amplifiers that generates

this powerful laser beam.

And then it basically comes out

and this is part of the
beam transport system

where it's brought to the machine.

So this pipe here has the big laser beam.

- And this has a mirror.
- [Marc] Yes.

- [Casper] Then the pulses travel

to the light source module.

It kind of looks like a Transformer

or like a, I don't know, like a spaceship.

There's so many wires going everywhere.

- [Marc] Don't touch this.

- [Casper] Holy crap.

This is pretty big, huh?

This is insane.

- [Marc] And this is
just the light source.

- [Casper] This is just a light source.

Are you getting this comparison shot?

- [Marc] And so you need all
of this just to make EUV light.

- [Casper] Just to make the
light, that's incredible.

Can we do a little walk around?

- [Marc] We can do a little walk.

- Let's go.

- So basically, this is
the heart of the source.

- [Casper] Can I stand on here?

- [Marc] If you are below 137, you can.

- [Casper] I don't, I think I am.

Woo.

And so the tin droplets are
coming in from the left.

- [Marc] Yes.

- [Casper] Then we're
shooting the laser from here.

- [Marc] Yeah.

- [Casper] Okay, it explodes.

- [Marc] And then the light.

- [Casper] The light goes out there.

One improvement from
ASML's first EUV machine

to their newest one is

the number of pulses that hit the droplet.

The first pre-pulse still
flattens the droplet

into a pancake,

but now there's also a second pre-pulse

that further reduces the density.

It basically turns it
into a low density gas,

it rarifies it.

And then the final pulse
essentially ionizes all of it.

So for basically the same power
coming from the drive laser,

they get even more EUV light.

Now if they want even more light,

then the only way to do that is

by hitting more droplets.

And that's exactly what they did.

- Our most recent EUV light sources

that we're shipping right now,

which are around the 500 watt level,

we increased the rep rate up
to 60,000 times per second.

And then we have a roadmap that's gonna go

to 100,000 droplets per second.

We've actually now already demonstrated

this 100,000 droplets
per second in the lab.

So it's not an if but a when.

- Crazy.

- [Marc] The three pulses
that we use to make

the pancake, to blow up
the pancake a little bit

and then to evaporate the pancake.

- [Casper] Yeah.

- The first two pulses,

they would be coming in
through this pipe here

and then the main pulse
with the big laser,

the laser beam would be
delivered through this pipe here.

- [Casper] Both the
high and low NA machine

shipping out right now use three pulses

and eventually they will hit
more droplets per second.

But the light source
is just one small part

of the full machine.

After bouncing off the collector mirror,

the EUV light moves to the illuminator.

A set of mirrors shape and focus the light

before it hits the reticle.

The reticle is the top half

and this module is built
in a separate facility

and installed later.

Next the light goes into
the projection optics box,

which is a set of mirrors
that shrink the light down.

The high NA machine can shrink the pattern

eight times in the vertical direction

and four times in the
horizontal direction.

The mirrors are also much smoother still.

If the low NA's mirrors
were the size of Germany,

the tallest bump would
be about a millimeter.

But if the high NA mirrors
were the size of the world,

the tallest bump would be

about the thickness of a playing card.

By the combination of both
of these improvements,

ASML was able to increase
the numerical aperture

from 0.33 to 0.55.

And finally, the light hits the wafer.

In order to print around
185 wafers per hour,

the reticle whips back and forth

at accelerations of over 20 Gs.

That's over five times the acceleration

of a Formula 1 car.

And this is some actual footage

of what that's like inside this machine.

And notice that this is not sped up.

But the crazy thing to
me about this machine

isn't how fast the reticle moves

or even how small it can print,

but it's just how insanely
accurate it needs to be.

The most any two layers can be off,

which is called the
overlay, is one nanometer.

That's five freaking
silicon atoms of precision.

That's insane.

- So typically what we
do as system engineers is

that we make a budget.
- [Casper] Yeah.

- So we say, hey, you
get, let's say a nanometer

and we divide then the nanometers

to smaller fractions.
- Right,

the nanometers total.

It's not like you group gets a nanometer.

- You get a nanometer, you get, no, no.

You get a nanometer in total, yes.

- [Casper] So you have to fight for the,

for your part of the nanometer.

- It's kind of cool to realize

that like every smartphone
nowadays has a chip

that is made with the machine

that was actually put together here.

So that's a cool thought.

- Take a look at this.

- [Marc] It's pretty massive, eh?

- [Casper] So big.

So do you cover it up?

- [Marc] Yes.

Had a customer fab, it will be
looking like a big white box.

I like it better like this.

- [Casper] Yeah, me too.

It's funny, you need such a big machine,

so much infrastructure

to make the tiniest things
we can make at scale.

- It's inversely proportional.

- Yeah, smaller you want to go,

the larger everything around it becomes.

After the machines are
assembled, tested and approved,

they are disassembled to
ship all around the world.

5,000 companies supply 100,000 parts,

3000 cables, 40,000 bolts

and two kilometers of hosing.

ASML ships their high NA
machine in 250 containers

spread out over 25 trucks

and seven Boeing 747s.

Despite all the doubt and setback,

EUV finally made it to manufacturing level

three decades after
Kinoshita's first images.

But even when almost the
entire world didn't believe

it would work,

there were some people at ASML who knew

that it was going to work
all the way back in 2010.

- Around 2001, we said let's do EUV.

And then we run into many challenges.

2010, we installed the
first system at a customer.

So it was installed in Korea.

There it was, this thing
I had been pursuing

for, you know, 13 years was

now standing at a
customer, producing wafers.

This for me was a moment I realized,

yes, we made the right bet.

- [Casper] Years later, Jos ran into

the man who helped
install the first machine.

- He's now a professor
at a renowned institute.

And I shared the story about my relief

and how great we made the decision.

(indistinct) said, "Yeah, yeah, yeah."

He said, "When you left and
you flew out after Christmas,

the thing broke down and it took

two months to get back up again.

And they almost fired me

for making the wrong decision."

We had some ups and downs along the way.

- [Casper] Yeah.

- But again, once I saw
the system installed

at a customer, in a customer fab,

I knew we had done the right thing.

This was 2010.

The first phone that came out was 2019.

So we still had some hurdles to resolve.

- [Casper] Right.

- But we kept going.

- Now, I have spent several months

working on this video
and thinking about it

and it still feels absolutely impossible.

And the more I think about it,

the more I think, you know,
those people 40 years ago

that said it was impossible,
they had a point.

It's completely unreasonable to think

that you could make this
artificial sun in a lab,

that you could make these mirrors

that are this smooth

and that you could get the
required overlay accuracy.

The reasonable thing is to think

that none of that is possible

and to point out all the
problems with each of them.

Which reminds me of this quote,

the reasonable man adapts
himself to the world.

The unreasonable one persists

in trying to adapt the world to himself.

Therefore, all progress depends

on the unreasonable man.

Imagine if Andy and
Kinoshita and all the others

had been reasonable,

we would have none of this.

In fact, imagine what
the world would be like

if everyone on it was reasonable.

It would probably be extremely boring.

Probably most of the technology,

most of the things you
enjoy on a daily basis

wouldn't be here.

In fact, you probably wouldn't be

watching this video,

because just about all
the technology we have

nowadays would seem
completely unreasonable

even just 200 years ago.

And so I really think
that to a large extent,

we owe our lives to those
unreasonable people.

And maybe at least to me,

it's a reminder that it's good
to be a little unreasonable,

at least in some of the big parts of life.

Changing the world is difficult.

It took overcoming thousands of obstacles

and over 30 years to get EUV to work.

But big breakthroughs usually
start in the same way.

That is, you learn, you
explore some related ideas,

you try to apply them in some new ways,

and then you build skills to take on

bigger and bigger challenges.

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