Inseparable From Magic: The Tech Behind ASML
Tiny suns, atomic mirrors, and the bottleneck behind every chip
Hey there 👋
I called TSMC ‘the most important company in the world’ in the title of my recent article here at SK NEXUS.
I called it so because it’s the only company that is manufacturing advanced semiconductors at a speed and precision that’s unmatched in the world.
And also because the two superpowers of our time (US & China) may go to war over that company.
However, it takes a lot of other important companies to make TSMC the most important one. And one of those companies is ASML.
ASML stands for Advanced Semiconductor Materials Lithography and this handful of an acronym simply means that this company does research and manufacture materials for semiconductors manufacturing.
Semiconductors are building blocks of brains of our computers - CPUs, GPUs, etc.
On paper, ASML feels boring. It’s a company based in the Netherlands that sells only a few dozen of its chip-making machines each year to only a handful of companies around the world.
When people talk about AI dominance, they talk about NVIDIA. When people talk about semiconductors, TSMC is the main thing. ASML doesn’t usually make headlines as much as other tech companies do.
Yet it’s one of the most valuable and important tech companies ever to exist not just in Europe but in the world.
For a first time reader, this doesn’t make sense. But if you look a bit closer, everything makes sense.
The dozen or so machines that ASML sells each year are their best kept secret.
The EUV (Extreme Ultraviolet) lithography machine as it is called is basically an atomic level printer that prints semiconductor chips.
ASML’s EUV machines are so cool that they’re able to create temperatures hotter than the Sun’s surface, the irony :p
It is a machine that relies on mirrors that take many months to polish and are smoother than physics feels comfortable with.
A machine so complex that replicating it would require rebuilding an ecosystem that took more than 16 countries and 20 years of R&D to produce.
That’s ASML. The only maker of EUV Lithography machines in this world. We have a whole section on EUV lithography machines that we’ll get to shortly.
Because of these EUV Lithography machines, ASML has quietly become one of the most strategically important companies in the world.
The rest of the article would provide a detailed answer as to why that is.
What Does ASML Do?
In our normal discussions whenever we come across the list of important tech companies in the world the answer almost always is a company like Google, Apple, or some other from the silicon valley.
Generally people love to talk about how NVIDIA is the only tech company to reach 5 Trillion dollar market cap but they often forget the companies that are powering the core technology behind the scenes. ASML is one of those companies.
ASML which stands for Advanced Semiconductor Materials Lithography (what a cool name) is a Dutch multinational company that makes the machines used in semi-conductor manufacturing.
Actually, ASML is the only company in the world that makes the Extreme Ultraviolet Lithography machines.
What’s “Lithography”, you might ask?
Lithography is a step in chip manufacturing where patterns are “printed” onto silicon wafers using light. Think of it like an insanely precise projector system.
You shine light through a mask, and that pattern gets transferred onto a photosensitive layer on the wafer.
Smaller patterns mean more transistors. More transistors mean more performance and more efficient chips. And the smaller you go, the harder it gets.
Do that process dozens of times. Stack layers. Add transistors. And you’ve got yourself a semiconductor chip.
Advanced semiconductor chips like those used in our PCs and smartphones are almost all built on ASML’s EUV lithography machines. Without EUV technology, there are no advanced chips to play with.
How Is ASML Different?
Generally, when you look at companies that are related to semiconductors you can divide them into two categories. These are:
Chip Designers - Companies like Apple, Nvidia are chip designers. They design the hardware specifications of chips. These designers come up with the features of a chip like how many transistors would it have, how much memory would the chip have and so on. These designers don’t physically make the chips.
Chip Manufacturers - TSMC, Intel, Samsung are chip manufacturers. These companies take designs from chip designers and physically manufacture those at scale inside their chip-making facilities. These companies are also known as fabs.
However, ASML is different. It doesn’t fall in either of the above categories. In-fact, it’s in a league of its own.
It is the only company in the entire world that supplies its sophisticated EUV lithography machines to all the chip manufacturers. These machines produce some of the most advanced semiconductor chips.
We’ll go into detail as to why it is the only company making these machines and what’s so special about them. But for now, just know that without ASML’s machines, fabs can’t build out advanced semiconductor chips.
Chip designers can move between fabs. Apple uses TSMC today, but Samsung manufactures for others. Customers can switch partners. Yields improve. Contracts shift.
If you want to make the most advanced chips in the world - 5nm, 3nm, 2nm - there is exactly one place to go for the machine that prints them.
ASML is the only company shipping extreme ultraviolet (EUV) lithography systems at production scale. Without it fabs don’t work and chip designs are useless.
Basically, we won’t have any iPhone launches if ASML suddenly stops existing one fine morning.
The Illegal Tech Behind EUV Lithography
I used the word ‘illegal’ because the technologies behind EUV feel illegal when you try to learn more and dive a bit deeper into their workings.
As a recent article in Financial Times put it, the working of an EUV machine consists of multiple impossible looking processes, all of which have to work 100% of the time at once for the EUV machine to work properly.
Basically, there is zero chance for error and these processes have to be repeated hundreds of times a single second.
Generally, chip manufacturing starts with a silicon wafer - a thin, ultra-flat disc of purified silicon (basically sand).
On that wafer, manufacturers build layer upon layer of circuits. Each layer contains patterns that define transistors, wires, and interconnects.
How do they create those patterns? They use light.....special light.
A light source shines through a mask containing the circuit design. That pattern gets projected onto a photosensitive material. After chemical processing, the pattern is etched into the silicon.
This process is repeated dozens of times.
Smaller patterns mean you can pack more transistors into the same area. That’s basically the infamous Moore’s Law in action.
For decades, chipmakers used deep ultraviolet (DUV) lithography. It worked fine as long as transistors were large enough relative to the wavelength of light being used.
Then we started hitting the limits of Physics because features of our chips started becoming smaller than the wavelength of light.
This means natural effects like diffraction started distorting the patterns that would be etched onto the silicon wafer.
And once you go that small you can’t just “focus harder.” You start hitting fundamental optical limits.
Engineers tried tricks. Multiple patterning. Complex processing steps. But costs ballooned and complexity just increased and increased.
That’s when EUV entered the scene which isn’t just an upgrade but a totally different universe. And producing the EUV light isn’t just hard. It’s borderline insane.
As someone who’s into science and technology, the technology behind EUV lithography just boggles my mind.
Producing the Extreme Ultraviolet Light
The process of EUV lithography starts with a special kind of light that is artificially produced by us humans. And it took us about 20 years of R&D just to get this light to a usable state in lithography.
EUV stands for Extreme Ultraviolet. It is a special kind of light that is produced through a complex process by ASML. This light is special because it has a wavelength in nanometers and that’s the only light today that allows us to build advanced chips.
To generate that light, ASML’s EUV machine fires powerful lasers at microscopic droplets of molten tin that are ~30 microns in size or about the size of a white blood cell in our bloodstream.
Each droplet is shot at the speed of 250 km/h and the machine’s goal is to shoot a laser on that droplet and convert each droplet into plasma.
That plasma reaches temperatures of about ~219,700 degree celsius or roughly 40 times hotter than the surface of the sun. And as a result of that explosion, EUV light is emitted.
Each tin droplet gets hit 3 times in 20 microseconds in a row. The first shot flattens the tin and the others vaporize it into plasma form. The last shots, then vaporize the metal into plasma.
Just pause for a second and read all of this again. The process of producing that EUV light is a man-made collision between a metal and a laser to create plasma hotter than the surface of the sun just to produce that EUV light.
If you’ve watched the recent movie Oppenheimer it opens with a quote that sits well in the EUV context too:
“Prometheus stole fire from the gods and gave it to man. For this, he was chained to a rock and tortured for eternity”
We are literally shooting lasers at molten metal 50,000 times in a single second to create mini suns inside a man-made machine, just so we can etch tiny lines onto silicon.
And it has to happen continuously, reliably, inside a factory running 24/7, no breaks, no downtime, no nothing!
Photolithography and Mirrors
The first job of ASML’s EUV lithography machines is producing the EUV light but that is only half the job because now we need to essentially print using that light, that’s where some special mirrors come in.