EUV (extreme ultraviolet lithography)

Chip circuits are drawn by shining light to print a pattern on the wafer. This step is called lithography. The shorter the wavelength of the light, the finer the lines it can draw. EUV uses extreme ultraviolet light with a wavelength of 13.5 nanometers to draw fine circuits that were hard to draw with earlier light.

This light is absorbed even by air and glass. So the inside of the machine is made a vacuum, and the light is bounced off very smooth mirrors instead of passing through lenses. It is so hard to build that only one company, ASML of the Netherlands, sells EUV lithography machines for chip production.

It is something like spraying paint through a stencil to print a picture. The finer the spray droplets, the more clearly even small patterns print. EUV is the finest spray.

Without these machines, it is hard to make the most advanced chips properly. Only one company makes them and there are few of them, so who gets how many, and which countries they can be sold to, often appear in chip news.