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Comment by sawyna | Hacker News Reader

Can you explain what EUV is? I'd prefer an ELI5!

Chips are made by etching lines into a special kind of glass. The etching is done with light. The smaller the light, the smaller the lines. Red light is big, violet light is small. Extreme ultra-violet light is really small, so they can etch really small lines. When the lines are small, the electricity moves through them more quickly, so the chip’s work gets done faster.

When the lines are smaller, you can place more transistors/functionality in the same area, which leads to higher performance. The power required decreases too.

Can you explain how the transistors are placed on the glass? Are they also "etched" by the EUV light?

They are etched and filled with different elements. So a traditional mosfet Transistor needs n, p and gate layers.

They are put on there by putting chemicals on specificatic places. Because it's such a complex pattern, it's easiest to use a template and spray the chemicals on, the same way some artists apply spraypaint.

The template is first printed on the glass. This is done by putting a light sensitive layer (photoresist) on the glass, and exposing some of it to light. When the light gets put on there the properties of the photoresist change so you can wash off the parts you don't want. Jl6 called this process "etching" (there may be additional steps that can also be described as etching, I don't know. Semiconductors are made with a lot of processes. This is the most well known process).

Then you spray on the chemicals you want, and then you wash away the remaining photoresist so you can put the next layer on.

This happens a lot of times for a modern chip.

Additional to what has been posted already, the shape of the lines (which ultimately will result in transistors) is defined by manufactured patterns on quartz glass photomasks[1]. AFAIK a modern processor design has a stack of around 40-60 masks placed in sequence for the light to pass through. Producing these photomasks follows a similar manufacturing process from a lithography POV, except that electron-beams[2] are used instead of a light source. The mask manufacturing process requires its own specialized machines and Intel owns companies that produce those, eg. IMS Nanofabrication[3].

[1]: https://en.wikichip.org/wiki/mask

[2]: https://en.wikipedia.org/wiki/Electron-beam_lithography

[3]: https://www.ims.co.at/en/

The last I heard was TSMC's mask count for 3nm chips is back at just under 100. EULV had brought it down but it's right up there again at the latest node. You really need to avoid those all-layer re-spins!

I looked around at several ELI5-type sources and honestly the Wikipedia one is the best I came across.

https://en.wikipedia.org/wiki/Wafer_fabrication

Here is ASML specifically, in a very slow slideshow format, representing our finest web technology.

https://www.asml.com/en/technology/all-about-microchips/how-...

So technically, we could use Xrays/Gamma rays to get even smaller.

If you had the requisite optics, perhaps.

https://en.wikipedia.org/wiki/X-ray_optics

So essentially, these chips are made by shining the design through a mask over a silicon disc coated with photoactive chemicals and then chemically processed to make that design "stick" depending on what parts were illuminated and what parts were not, much like old school photography. There's no physical etching going on, its a chemical process where light is used to "activate" certain parts of a coating.

The wavelength, or the color of the light here limits how much minified image we can shine and currently the Extreme ultraviolet lithography(EUV) is the state of the art where they use ultraviolet light with 13.5nm wavelength. As different materials behave differently under different light wavelengths, EUV requires different process to shine the mask over the silicon disk. One major difference from the previous processes is that in EUV lithography they use mirrors instead of lenses to direct the light.

So far, it's only the European manufacturer ASML who managed to perfect this process for mass production.

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