Original subtitles

Inside every modern laptop, smartphone,

desktop computer, advanced AI server, or

practically any other high-tech device

are cuttingedge microchips such as these

CPU, GPU, SOC, DRAM, and SSD chips. Each

with tens of billions of transistors

inside of them. The transistors inside

these microchips are incredibly small

with the tiniest features measuring

around 10 nanm or 45 silicon atoms. This

feat of science and engineering may seem

impossible because on one hand each of

these microchips is made from connecting

billions upon billions of transistors

together and then on the other hand each

individual transistor is only nanometers

in size. Additionally, these microchips

are everywhere and in everything and

therefore they must be reliably mass-

prodduced. So, how is manufacturing such

a microchip even possible? These are

photoiththography tools and they're the

key to manufacturing microchips.

However, it's important to note that

there are dozens of different types of

tools used in the various steps for

making microchips and each one plays a

critical role in the manufacturing

process. So to be accurate,

photoiththography tools are the ones

that are used to copy and imprint the

nanoscopic patterns of transistors and

layers of wires onto a microchip. And

therefore a useful analogy is to think

of these photoiththography tools as

nanocale microchip photocopers.

Photoiththography tools have been

continuously evolving to copy and

imprint smaller and smaller transistors

and circuitry. And in this video, we're

going to dive into this state-of-the-art

EUV photoiththography system and explore

the science and engineering inside of

it. So, let's begin with a quick

overview. To start, the EUV lithography

machine takes the design of a single

layer of a microchip on what's called a

photo mask and loads it into the

machine. Next, a 300 mm silicon wafer

with a set of prior processes applied to

it is placed onto a wafer carrier inside

the machine. With both in place, the

machine uses extreme ultraviolet light

or EUV and a set of mirrors to copy the

design from the photo mask onto a

silicon wafer. The wafer moves to the

next position and the microchip design

is copied yet again. This copying

happens over and over until the wafer is

filled with a 100 or more microchips and

then a new wafer comes in and the

copying starts over. This is the

realtime speed of the lithography

machine taking about 18 seconds to

duplicate the same microchip design

around a 100 times across the entire

area of a 300 mm wafer. Let's take a

look at one of these microchips and see

what exactly we're copying. Inside this

microchip are approximately 30 billion

transistors. And if you were wondering,

it's the design of a GPU or graphics

processing unit found in the center of a

graphics card. When we zoom into a

nanoscopic view of this microchip, we

find a 3D maze of transistors and layers

upon layers of wires with the smallest

dimensions of the bottommost layers

measuring around 10 nanometers or around

45 silicon atoms. Specifically, the EUV

photoiththography system typically

patterns the lower layers with the

smallest features, whereas other

photoiththography tools are used to

pattern the higher layers. It might be

difficult to fully grasp the level of

detail and complexity inside a single

layer of billions of nanoscopic

transistors. So let's use a thought

experiment and pretend that instead of

copying transistors and wires, this EUV

photoiththography system is used to copy

the text from a book. If the width of

each line of a letter is 13 nm, then the

word cat would take up around 155x 240

nm. A page of text would be about the

size of a red blood cell and a chapter

of a book would be a grain of pollen.

When we zoom out to see the equivalent

area of a GPU chip, how many pages of

text do you think we could fit using

these nanoscopic letters? Well, we could

print all seven Harry Potter books, plus

every book written by Stephven King, the

entirety of the text from the English

Wikipedia, and still have enough space

to fit every single book from your local

public library. There's an unbelievable

quantity of nanoscopic lines and details

that can fit into the area of a

microchip. And it's all photocopied by

this EUV lithography system in less than

a second. It's no exaggeration to say

that every piece of modern technology

that you use is made possible by this

machine. And in this video, we're going

to explore the key modules inside it and

see how they work. So, let's jump right

in.

This video is sponsored by ASML, the

company that designs and manufactures

EUV lithography systems. Throughout the

video, all the details and facts were

independently researched, written, and

animated. Additionally, some aspects are

simplified and due to the proprietary

knowledge and confidentiality around EUV

lithography, some of the details we

present are approximated or modified.

Before we open up and explore this EUV

system, let's first spend a few minutes

discussing microchip manufacturing and

semiconductor fabrication plants or fabs

for short and the exact role of this

machine. Inside our example fab are

hundreds of machines of which a couple

dozen or so are the EUV lithography

machines we've been discussing. To make

a microchip, 300 mm silicon wafers are

stacked inside a front opening universal

pod or FOP and carried from machine to

machine using an overhead transport

system. The FOP is lowered onto a

machine where each wafer is processed in

one way or another. And once the machine

completes its work, the wafers are

returned to the FOP. The pod is picked

up, carried to the next machine, and

dropped off for the next step in the

process. Microchip manufacturing is

incredibly complicated. But a simple way

to think about it is that it's kind of

like spray painting a design through a

stencil, but instead of art, this

stencil contains the nanoscopic patterns

used to build the transistors and wires.

Inside the microchip factory, some tools

are used to build a stencil such as the

EUV lithography system and many of the

other machines such as the deposition

tools or ion implanters are the spray

paint. So let's take a look at how we

build the stencil on the wafer which is

technically called a photoresist layer.

To begin, the wafer travels to a machine

called a track tool where a light

sensitive material called photoresist or

just resist is poured on and evenly

spread across a spinning wafer. Next,

the wafer is heated in order to dry and

solidify the resist, thus forming a flat

blank stencil. The wafer then moves to

the photoiththography tool where EUV or

extreme ultraviolet light is projected

onto the photo mask, which is also

called a reticle, but typically just a

mask for short. When EUV light hits the

mask, the patterned information is

imprinted in the light. And this

imprinted light then bounces off a set

of mirrored lenses in order to project a

focused and scaled down image of the

mask onto the wafer. Wherever the EUV

light touches, the resist is modified

and thus the design is copied from the

mask onto the wafer. The wafer moves to

the next position and the EUV patterning

process repeats again until the entire

wafer is filled with copies of the

design from the mask. Next, the wafer

travels back to the track tool where the

modified resist is washed away using a

developing solvent and the water is

heated to form a hardened stencil or

completed photoresist mask layer on the

top of the wafer. Now that the wafer is

patterned, the wafer travels to the

other spray paint-like tools in the fab

which are used to etch away the

uncovered areas, implant dopens such as

boron or phosphor or deposit a layer of

copper, tungsten or other metals,

thereby building a single layer of

nanoscopic structures. Note that there

are additional process steps that we're

not going to get into.

Now that we have a basic understanding

of how the stencil and spray paintlike

processes form a single layer, let's

zoom into a nanoscopic view inside a

microchip where we can see how the

transistors and wires are incredibly

complicated three-dimensional

structures. Each of these layers are

built one after the other. Starting with

the transistors at the bottom, moving up

to the small wires, and then wider and

wider metal layers further up. In

essence, to build a complete microchip,

the stencil and spray paint process is

repeated over and over each time,

building only a single layer. And

therefore, it's more effective to

visualize these processes as a loop,

where a single pass of the loop forms

one layer using a single mask design in

the lithography tool, and then another

layer is built using an entirely

different mask loaded in the machine. To

complete a GPU chip like this one, the

series of process steps or loops is

repeated around 80 times, resulting in

around a thousand individual process

steps and taking four or so months to

complete.

Let's go back to the nanoscopic view of

the microchip. Here we can see that the

lower layers are incredibly tiny and 13

nanometer EUV light is used to build the

pattern for these layers. However, the

upper wires are substantially larger and

are patterned using an entirely

different machine called a DUV or deep

ultraviolet photoiththography system

which is also built by ASML and uses a

deep ultraviolet wavelength of light.

DUV lithography tools were introduced in

the 2000s and are still incredibly

advanced machines. Because DUV tools

typically cost less than EUV machines,

it's more cost effective to use EUV

tools to pattern the transistors and

so-called critical layers and then use

DUV tools to pattern the upper, wider,

less critical layers. Additionally, less

advanced chips that don't require the

smallest transistors and wires may

forego using EUV lithography altogether

and only use DUV wavelengths such as

193, 248 or 365 nanometers.

As a result, cuttingedge fabs typically

utilize different types of lithography

tools and all these machines work as an

intricate ecosystem to make a microchip.

With the basics of microchip

manufacturing covered, let's open an EUV

lithography system, explore the

incredible science and engineering

inside, and divide the system into its

five key parts. the light source, the

illuminator, the reticle handler and

reticle stage, the projection optics,

and finally the wafer handler and wafer

stages. We'll begin with the light

source which produces the EUV light. But

let's first answer the question of why

we even need to use extreme ultraviolet

light. Well, a simple analogy is to

think of the light used to project and

copy the pattern from the photo mask as

the tip of a mortar. And as you're

probably familiar with markers, if you

want to draw thin lines, then you need a

marker that also has a thin tip. You can

do tricks like angling the marker, but

if you want to draw lines that are 100

times thinner, well, then you need to

switch pens and use a much smaller fine

tipped pen. Likewise, to copy designs

with dimensions only around 10 nanm

wide, we use 13 nanmter light, which is

in the extreme ultraviolet light range

of the electromagnetic spectrum. The

more technical answer deals with the

wavelike nature of light, and what

happens when light hits these nanoscopic

patterns inside the photo mask. These

patterns are made from nanoscopic EUV

absorbing blockers on top of a surface

that reflects EUV light. We'll explore

the photo mask and how the system uses

reflective lenses a little later in this

video, but for now, instead of using

reflective optics, it's easier to

visualize the photo mask as through beam

optics in a setup similar to the

well-known double slit experiment.

However, instead of the double slit,

we're showing light passing through a

complicated pattern of nanoscopic slits

that represents a small portion of the

overall photo mask. So, what happens

when we use a wavelength of light that's

substantially larger than the 13 nm EUV

light, such as this 450 nm blue light.

Well, when this large wavelength light

hits the pattern, the pattern is almost

entirely lost. This is due to the width

of the holes in the pattern being

substantially smaller than the

wavelength of light hitting it. This

limit to the resolving power of the

lithography machine is described in

criterion equation which we will explain

later. So, let's switch to 13 nanmter

EUV light. As the EUV light hits the

pattern, the light passes through and

the pattern of the photo mask is

imprinted into the light and the light

defracts similar to the double slit

experiment. This imprinted light then

passes into the projection optics

mirrored lenses which are used to focus

and scale down the pattern and project

it onto the wafer. So now that we

understand the need for EUV light, the

next question is how do we produce it?

To start, two high-powered laser pulses

run through multiple amplifiers below

the clean room floor. These laser pulses

grow in power and then travel from the

subfab using a pathway of mirrors and up

through the bottom of the tool and into

a chamber called the source vessel. The

first laser, called a preulse, is around

5 kW in power and is targeted at a

droplet of tin using a set of actuated

mirrors. This prepulse laser turns the

tin droplets into a pancake- like shape.

The second approximately 25 kowatt main

laser pulse, which is more than 10 times

stronger than the lasers used to cut

steel, hits the tin pancake, instantly

vaporizing it and turning it into

glowing plasma. Within each of the tin

atoms, some electrons are ejected and

others are kicked up to higher energy

states. When electrons drop back down

from the 4F to 4d orbitals, 13 nanometer

EUV light is produced. Shooting two

laser pulses at a droplet of tin might

seem like a rather obscure process.

However, EUV light doesn't naturally

occur on Earth, and it's one of the few

ways to efficiently produce over 500

watts of EUV light. Additionally, the

reason for using tin is that its plasma

produces a wide range of wavelengths

with a clear peak at 13 nanometers.

So, where does the tin droplet come

from? Well, over here, a solid ingot of

ultra pure tin is melted and fed into a

storage tank and then piped towards a

microscopic nozzle. A po electric

transducer squeezes the tip of the

nozzle and due to high pressure nitrogen

inside the storage tank, a droplet of

tin is forced out at a speed of 100 m a

second. Next, high-speed cameras measure

and calculate the trajectory of the

droplet and feed the data to a set of

actuated mirrors in order to angle the

laser pulses to precisely hit the tin.

To control the amount of EUV light,

sometimes droplets are skipped by the

lasers and these droplets are captured

over here. This process of producing

high-speed tin droplets and then

shooting them with two laser pulses to

generate EUV light happens at a rate of

50,000 times a second. Now that we have

EUV light, the first mirror called the

collector focuses all the EUV light to a

small hole called the intermediate focus

which only EUV light can pass through.

The light next enters into the

illuminator which is composed of the

field facet mirror, the pupil facet

mirror and another set of mirrors. These

mirrors are so perfectly shaped that

there's less than an atom's deviation

from the surface. The illuminator takes

this EUV light and shapes it into a thin

ribbon that has equal uniformity across

a well-defined range of angles before it

hits the photo mask. Using an equal

uniformity of light at all angles is

critical to imprinting a perfect

nanoscopic pattern from the mask via the

light and onto the wafer. We want to

take a short detour and mention that

this has been a rather challenging video

to make simply because there's a

mountain of science and engineering

inside these machines built by ASML and

this video only explores the tip of the

iceberg. Essentially, a lot of the

details had to be cut in order to keep

this video a manageable length. For

example, EUV light is incredibly

difficult to work with because it's

absorbed by atmospheric molecules and

therefore the entire light path and

wafer carrier stage is connected to

vacuum pumps which remove all the air.

Additionally, EUV light is absorbed by

glass and practically all other

materials and therefore to focus and

transport the light this system uses

mirrors rather than transmissive lenses.

However, these mirrors called Brag

reflectors are nothing like the mirrors

in your bathroom, but rather they're

composed of dozens of alternating layers

of silicon and malibdinum, each only a

few nanometers thick. When EUV light

hits the surface of this brag reflector,

only 3% is reflected at each boundary

layer while the rest passes through. But

with so many layers, the cumulative 3%

reflections add together using

constructive interference, resulting in

a total of 70% being reflected for a

single mirror, while 30% of the light is

lost and absorbed. However, with more

than 10 mirrors in the optical system

and only 70% reflection at each one, the

final light hitting the wafer is less

than 10% the brightness of the light

emitted by the tin plasma, which is why

the initial light from the source vessel

needs to be as bright as possible.

Another example of the incredible

engineering inside this machine is that

this field facet mirror is assembled

from hundreds of independently

controlled mirrors that can be angled to

direct the light onto specific regions

of the segmented pupil facet mirror.

Together these two mirrors take the cone

of EUV light from the intermediate focus

and turn it into a complex pattern of

illumination. For example, this is

called annular illumination. Here's

dipole illumination and then here's

quazar illumination.

You're probably wondering why we require

such complicated patterns of

illumination. Well, when we look back at

the microchip, one layer of wires is

running mostly horizontally. The next

layer is a set of cylinders called VAS.

And then the following layers have wires

that run vertically. And each layer uses

a different mask. Earlier we said that

the EUV light is kind of like the tip of

a fine tipped pen. Having different

patterns of illumination is like holding

the marker at different angles with

respect to the lines or circles that are

being patterned. Specifically, annular

illumination is best used to pattern the

layers containing vas and is like

holding the marker straight up and down.

Whereas dipole illumination like this is

best used to pattern lines running

horizontally. And then we rotate the

dipole illumination for patterning the

vertically oriented wires.

Imagine being at the forefront of this

groundbreaking science and engineering.

Then picture ASML, whose work powers the

innovations that solve some of

humanity's toughest challenges in

energy, mobility, and healthcare. ASML

is a leader in photoiththography

systems, serving as the backbone for the

world's leading chip makers and enabling

the technology that drives our future.

With over 44,000 talented individuals

and growing, ASML is headquartered in

the Netherlands with major R&D and

manufacturing sites in the US and Asia.

Their sprawling campus is not just a

workplace. It's an exceptional

environment where cutting edge

technology comes to life to keep pushing

the boundaries of what's possible. ASML

seeks exceptional talent. They are

looking for scientists and engineers

ready to design the nextgen lithography

systems, technicians and logistics

experts eager to build, ship and support

these groundbreaking systems, and

software developers passionate about

working in a world of nanometers. ASML

is the next step for those ready to make

an impact in an inspiring setting.

Together with their suppliers, partners,

and customers around the world, they're

committed to powering technology

forward. Visit their website using the

link in the description to learn more

and start a journey with ASML. Today,

let's move on to the next part of this

EUV lithography tool and explore the

photo mask or mask, which is also called

a reticle and contains the entire design

of a single layer of a microchip. The

mask starts in a doubly sealed pod and

is loaded onto the machine using an

overhead transport system. The outer

protective carrier is opened and a

robotic arm picks up the inner pod and

carries it to a vacuum load lock. The

chamber is sealed and pumped down to a

vacuum and the inner door opens. Next,

the inner pod opens up and a separate

robotic arm carries the mask and base to

an inspection station. Each mask has a

half a dozen different marks, including

a barcode, as well as fiducials, which

are designs used to align the mask with

subnanmter level accuracy. The mask is

carried over to and loaded onto the

reticle stage, which moves back and

forth across the EUV beam with

incredible accuracy and at high speeds

with more than 7 gs of acceleration.

This mask's surface is built from the

same Bragg reflector surface mentioned

earlier, but with a pattern of absorbers

on top that locally blocks the light in

order to create the detailed microchip

layer pattern. This 6x6 in mask has a

pattern area of 104x

132 mm and an absorber pixel resolution

of below 10x 10 nm. In the beginning of

this video, we showed a variety of

different chips with different sizes.

And shortly after, we showed a GPU being

patterned across the wafer. The pattern

on the mask is four times larger than

the microchip. And this GPU chip is

close to the maximum size chip that can

fit on the mask and therefore only one

copy fits, resulting in 90 GPU chips

fitting onto a 300 mm wafer.

However, CPU chips are typically smaller

and therefore in the following example,

we can fit two copies on the mask and a

total of 185 chips on the wafer. When we

look at even smaller DRAM chips, 12

copies can fit on the mask, yielding 978

chips on the wafer. Technically, the

exposure field is one scan of the mask

onto the wafer. And an exposure field

can have anywhere from one to a dozen or

more die patterns on it, yielding around

a hundred to a thousand or more chips on

a single wafer. This mask contains an

incredible amount of information. And as

mentioned in the intro, it has the

equivalent amount of detail as all the

text of Wikipedia plus all the books in

an average public library. This mask,

which can cost around $300,000,

must be so perfect that using our

analogy, there can't be a single

grammatical error, spelling mistake, or

even an extra curve on a letter across

21 million pages of text. Otherwise, it

would damage every chip on the wafer.

Also, if you're curious, here are the

calculations we used for the transistors

to text and book conversions. Pause the

video to work it out. The next topics

we'll explore are the projection optics

and how the wafer is moved around the

machine. But first, we'd like to mention

that this video topic is incredibly

complicated and took hundreds of hours

to research, write, model, animate, and

edit totaling over,00 hours. So, if you

could take a few seconds to like this

video, subscribe, comment with a quick

message below, and most importantly,

share it on social media and with a

friend, family, or work colleague. It

would help far more than you think.

Additionally, we have a Patreon page

with AMAs and behindthe-scenes footage.

And if you find what we do useful, we

would appreciate any support. Thank you.

So, let's move on to the projection

optics. These optics are composed of a

series of mirrors that are used to

project and focus the patterned EUV

light onto the wafer with extremely high

accuracy while minimizing wavefront

aberrations and shrinking the image by a

factor of four. These mirrors are

designed and manufactured by Zeiss who

is a longstanding partner of ASML and

has been a vital collaborator in the

development of the optic systems inside

photoiththography tools. To understand

the projection optics, we have to

discuss what determines exactly how

small these wires can be. And for this,

criterion equation is used. This

equation states that the smallest

dimension or critical dimension is equal

to K1 times the wavelength of light or

lambda divided by the numerical aperture

or NA. The wavelength of EUV light is 13

nm. K1 is the process factor which

relates to the various illumination

settings created by the field and pupil

facet mirrors that we discussed earlier

along with the photo resist and other

factors and is close to.3 for this

machine. Finally, numerical aperture or

NA is a measure of the angle and amount

of light the mirrors in the projection

optics can capture and focus onto the

wafer. Numerical aperture isn't just

about increasing the brightness of the

EUV light, but rather it's more of a

measure of the angles and amount of

constructive interference wave paths

that hit the mask and then are projected

onto the wafer. In short, with a larger

numerical aperture or NA, which

corresponds to a larger angle between

the projection mirrors and focal point,

we can achieve a smaller resolution.

This tool has a numerical aperture of

0.33.

However, the next generation of EUV

lithography systems called high NA

increases this to 0.55

resulting in an 8 nanometer critical

dimension. Increasing the numerical

aperture to 0.55

requires significantly larger mirrors,

which results in a redesign of the

entire optic system and other parts of

the machine, thus considerably

increasing the size and cost of the

system.

We could spend an entire video

discussing the next generation high NA

tool, but instead let's move on to

discuss the wafer transport system and

wafer stage and see how a wafer makes

its way to the EUV exposure station.

Let's start with a wafer that's carried

in a FUP on the overhead transport

system. This FUP lands on the

lithography cluster which is a

combination of a wafer track tool and a

lithography tool. The wafer first enters

the track tool where a layer of

photoresist or resist for short is

evenly spread across the wafer. The

wafer moves to another area inside the

track tool where it's heated in order to

dry and solidify the resist. Next, using

robotic arms, the wafer is carried from

the track tool into a vacuum load lock

inside the EUV tool. The pneumatically

actuated doors close and the chamber is

pumped down to a vacuum. Next, the back

doors of the load lock open up and a

different robotic arm carries the wafer

to one of the wafer stages. This system

is called a twin scan because there are

two complete wafer stages that

concurrently move two wafers around. The

key idea is that while one wafer is

actively being patterned, a second wafer

is being loaded onto the wafer stage and

measured under an alignment sensor.

Nanometer level accuracy is crucial with

these machines. And one key philosophy

of ASML is matan is vaten which is Dutch

for to measure something is to know

something. The reason for acquiring this

level of perfection is that when we look

at the nanoscopic layers of the

microchip which has wires and holes that

are only 10 to 20 nm wide. If one layer

is more than a couple nanometers off the

previous layer, then the electrical

connections won't conduct electricity

correctly. And if an entire layer is

off, then every single chip will be

catastrophically destroyed. To make sure

that the layer being patterned is

perfectly aligned with the previous

layer, the entire wafer is thoroughly

measured by the alignment sensor. On the

wafer are hundreds of alignment marks,

which are reference patterns that assist

in determining the exact position of the

earlier layers of patterns. The

alignment sensor meticulously measures

the X and Y positions of every alignment

mark on the wafer and builds a highly

accurate 2D map from the results. This

map shows some regions of the wafer

being biased in one direction by a few

to dozens of nanometers and another

region being biased in a different

direction. Additionally, the leveling

sensor uses grazing incident light to

measure the exact height of the wafer

and builds a topological map of the

wafer, which is critical for later

bringing the wafer stage to the position

such that the EUV light is perfectly

focused onto the wafer.

Now that we've measured and built the

exact alignment and height map for the

wafer, the wafer stage next moves to the

EUV exposure station. As the wafer is

being patterned, the wafer stage moves

in perfect synchrony with the reticle

stage, but only a quarter of the

distance due to the 4:1 reduction. At

the same time, the stage makes nanocale

adjustments using the alignment map so

that the new layer perfectly aligns with

the previous layer. When the wafer stage

moves from one exposure field to the

next, it's important that no EUV light

hits the wafer and thus a shutter

positioned up here near the reticle

stage closes. Once the wafer stage is

positioned to pattern the next

microchip, the shutter opens and the

wafer stage and reticle stage move in

perfect synchrony again. This process

repeats until the entire wafer is

patterned taking around 18 seconds in

total. So then what actually happens as

EUV light hits the photoresist?

Well, resist is a polymer mixed with a

photo acid generator. When high energy

EUV photons hit the resist, the light

ionizes it, releasing high energy

electrons. These electrons then hit the

photo acid generator, producing an acid

that breaks apart the polymer, making it

weaker. As a result, the areas hit by

the EUV light become soluble and are

washed away by a developing liquid in

the subsequent process step. One detail

is that the resist has an extremely high

contrast, meaning that at a certain

level of EUV light, the entirety of the

resist hit by that light is broken down.

This is critical in producing sharp

patterns and walls on the resist.

Let's next explore how the wafer and

wafer stage move around. Specifically,

the wafer stages levitate on a large

magnetic table composed of more than a

thousand magnets. Electromagnets on the

underside of the wafer stage move it

along this magnetic table both quickly

and with micrometer level accuracy while

intererometers on the top of the stage

measure its exact position. And this

setup is called the long stroke stage.

In order to secure the wafer, it's

placed on a plate, which is technically

called an electrostatic clamp. The clamp

cycles zones of high voltage across the

backside of the wafer to keep it in

place, a phenomenon similar to sticking

a balloon to a wall using static

electricity. To reach nanometer level

accuracy, the plate is independently

moved using smaller motors, which is

called the shortstroke stage.

By combining the long stroke and short

stroke stages along with measurement

encoders, the machine can quickly move

the wafer as it's being patterned and

maintain an accuracy of less than 1

nanmter or approximately four silicon

atoms. Once all the microchip patterns

are copied to the wafer, the stage moves

back towards the robotic arms where the

wafer is unloaded and placed into one of

the vacuum load locks, pumped back to

atmosphere, and then a separate robotic

arm brings the wafer back to the track

tool where the patterned and modified

resist is washed away using a developing

liquid. Finally, the wafer is heated

again to further harden the remaining

resist. The patterned wafer is then

loaded back into the FOP which is picked

up and brought to a different tool to

undergo processing in other ways.

Let's close this tool. And that's it for

our journey into photoiththography.

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Thanks for watching to the end.