The Invisible Trillion · Sand, Light, and the World’s Most Precise Factories

Step 7: EUV — The Most Absurd Machine on Earth

The current state of the art is extreme ultraviolet lithography, or EUV. The light used has a wavelength of 13.5 nanometers. That is about 30 times shorter than the shortest visible light. It is, technically, a form of soft X-ray.

Here is how you generate EUV light. You get a tiny drop of molten tin, about 30 micrometers across. You drop it through a vacuum chamber. As it falls, you hit it with a high-power carbon dioxide laser — first a small pulse to flatten it into a pancake, then a much bigger pulse to vaporize it into a plasma hotter than the surface of the Sun. The plasma, briefly, emits EUV light. You catch some of that light with a curved mirror and bounce it through a series of other mirrors — ordinary lenses don’t work for EUV because EUV is absorbed by basically everything, including air — and eventually onto the wafer.

You do this 50,000 times per second. One tin droplet, two laser pulses, one flash of EUV, fifty thousand times a second, for the entire time the machine is running.

The mirrors that carry the EUV light are themselves miracles. EUV is absorbed by glass, by quartz, by almost any material. The only thing that reflects EUV efficiently is a multilayer stack of about 100 alternating layers of molybdenum and silicon, each about two nanometers thick, deposited with atomic precision. Even these mirrors only reflect about 70% of the light that hits them. After bouncing off a dozen mirrors in the machine, only a few percent of the original light reaches the wafer.

The machine that does all of this — called an EUV scanner — is built by exactly one company in the world, a Dutch company called ASML. Each scanner:

• Contains about 100,000 precisely-engineered parts.
• Costs about $350 million.
• Weighs 180 metric tons.
• Ships from ASML’s factory in the Netherlands to the fab in 40 shipping containers, typically via a dedicated fleet of Boeing 747 cargo planes (because shipping by sea takes too long and doesn’t handle vibration well enough).
• Takes several months to install and calibrate.
• Is so sensitive that the gravitational pull of the Moon causes small but measurable shifts in its alignment, which have to be corrected for.

ASML has a backlog of orders that stretches years into the future. Every leading-edge chip fab in the world has to buy their EUV machines from this one factory in one Dutch city. If anything happened to ASML, the chip industry as we know it would freeze.

This situation — the entire advanced computing industry depending on a single Dutch company, which in turn depends on a single Belgian company (Zeiss SMT) for the mirrors — is one of the strangest facts about the modern world. Most people don’t know it. Now you do.

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